Rifabutin is an oral antimycobacterial agent. A derivative of rifamycin, rifabutin has been shown to be effective as a prophylactic agent against disseminated M. avium complex in patients with AIDS. Rifabutin is recommended as an alternative to clarithromycin or azithromycin for primary Mycobacterium avium complex prophylaxis in HIV-infected patients. Rifabutin is also considered an alternative to rifampin for tuberculosis and tuberculosis prophylaxis in HIV-infected patients when the organism is likely to be resistant to isoniazid. Rifabutin was approved by the FDA as a priority drug in December 1992.
General Administration Information
For storage information, see the specific product information within the How Supplied section.
Tuberculosis
-Directly observed therapy (DOT) is recommended for all children as well as adolescents and adults living with HIV.
Route-Specific Administration
Oral Administration
-May be given with or without food, although administration with food reduces gastrointestinal irritation.
-If needed, the capsules may be opened and the contents mixed with food such as applesauce for administration.
Extemporaneous Compounding-Oral
NOTE: Extemporaneously compounded oral rifabutin suspension is not FDA-approved.
-Shake well before administering. Measure dosage with calibrated measuring device.
Extemporaneous preparation of 20 mg/mL rifabutin oral suspension*
-Empty the powder from eight 150-mg rifabutin capsules in a glass mortar.
-Add 20 mL of vehicle (1:1 mixture of Ora-Sweet and Ora-Plus or Cherry Syrup) and mix to a uniform paste.
-Transfer the mixture into an amber plastic bottle.
-Pour an additional 20 mL of the vehicle into the mortar and mix.
-Add this material to the bottle.
-Repeat with enough vehicle to bring the final volume to 60 mL.
-Label the bottle with 'Shake well before use'.
-Storage:
--Prepared using Ora-Sweet and Ora-Plus: The suspension is stable for 12 weeks at 4, 25, 30, and 40 degrees C.
-Prepared using Cherry Syrup: The suspension is stable for 12 weeks at 4, 25, and 30 degrees C and for 8 weeks at 40 degrees C.
GI intolerance was a primary reason for discontinuation of therapy with rifabutin . Gastrointestinal adverse reactions reported in 1rifabutin-treated patients include abdominal pain (4%), anorexia (2%), diarrhea (3%), dysgeusia (3%), eructation (3%), flatulence (2%), dyspepsia (3%), nausea (6%), vomiting (1%), and nausea plus vomiting (3%).
Urine discoloration occurs in 30% of study patients receiving rifabutin compared to 6% in controls. Contact lens discoloration, skin discoloration (< 1%), and discoloration (brown-orange) of tears, perspiration, feces, saliva, and sputum also can occur.
The incidence of neutropenia (25%) was significantly greater than in patients treated with placebo (20%, p=0.03). Thrombocytopenia (5%), anemia (6%), eosinophilia (1%), and leukopenia (17%) have been observed during rifabutin therapy. Although the incidence has not been significant when compared with placebo, rifabutin has been clearly linked to thrombocytopenia in rare cases. One case of thrombotic thrombocytopenic purpura (TTP) has been reported. Hemolysis has been reported in < 1% of patients. Other events noted in post-marketing reports include pancytopenia, white blood cell disorders (including agranulocytosis, lymphopenia, granulocytopenia, decreased white blood cell count, decreased neutrophil count), and decreased platelet count.
Myalgia was reported in 2% of patients during rifabutin clinical trials. Arthralgia and myositis were noted in < 1% of patients during trials.
Uveitis with ocular pain and visual impairment has been reported rarely with rifabutin therapy. It was generally associated with doses greater than 1500 mg/day, however, uveitis was reported in 2 patients receiving drug regimens including rifabutin administered at doses of 600 mg/day PO and in four patients receiving only 300 mg/day PO, although these 4 patients were also receiving fluconazole, a known inhibitor of hepatic metabolism. In 4 patients, uveitis developed only after 7 months of therapy. In a study of HIV-positive patients receiving combination therapy for MAC bacteremia, 24 of 63 patients receiving 600 mg/day and 3 of 53 patients receiving 300 mg/day developed uveitis. The onset was at a median of day 42. Although these patients were receiving other drugs concomitantly, clinicians should be aware of this adverse reaction to rifabutin at potentially lower doses.
General adverse events reported during rifabutin clinical trials include asthenia (1%), chest pain (unspecified) (1%), fever (2%), headache (3%), and unspecified pain (1%). Flu-like syndrome and chest pressure or pain with dyspnea were reported in < 1% of patients. Flu-like symptoms, including fever, headache, chest pain, and dyspnea may indicate rifamycin hypersensitivity. Discontinue rifabutin if these symptoms occur and administer supportive measures
Insomnia was reported in 1% of rifabutin patients during clinical trials. Other adverse events occurring in < 1% of patients during trials include seizures, paresthesias, aphasia, and confusion.
Rash (unspecified) was reported in 11% of rifabutin patients during clinical trials. Other immune system reactions noted in post-marketing reports include hypersensitivity, and bronchospasm. In general, hypersensitivity to rifamycins have been reported an may include flu-like symptoms (weakness, fatigue, musculoskeletal pain, nausea, vomiting, headache, fever, chills, aches, rash, sweating, dizziness, shortness of breath, chest pain, syncope, palpitations), bronchospasm, cough, hypotension, urticaria, angioedema, conjunctivitis, thrombocytopenia, and neutropenia. Discontinue rifabutin if these symptoms occur and administer supportive measures.
Hepatic adverse events reported during rifabutin clinical trials include hepatitis (less than 1%), jaundice (less than 1%), and elevated hepatic enzymes (9% or less). Most combination therapy for active TB disease includes more than 1 agent that may contribute to hepatotoxicity.
Non-specific ST-T wave changes on electrocardiogram have been reported in < 1% of patients during rifabutin therapy.
Microbial overgrowth and superinfection can occur with antibiotic use. C. difficile-associated diarrhea (CDAD) or pseudomembranous colitis has been reported with rifabutin. If pseudomembranous colitis is suspected or confirmed, ongoing antibacterial therapy not directed against C. difficile may need to be discontinued. Institute appropriate fluid and electrolyte management, protein supplementation, C. difficile-directed antibacterial therapy, and surgical evaluation as clinically appropriate.
There have been postmarketing reports of severe cutaneous adverse reactions (SCAR), including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP), associated with rifabutin use. If patients develop a skin rash, monitor them closely and discontinue rifabutin if lesions progress. For DRESS, a multi-system potentially life-threatening event, the time to onset of the first symptoms may be prolonged. DRESS is a clinical diagnosis, and its clinical presentation remains the basis for decision-making. An early withdrawal of rifabutin is essential due to the syndrome's mortality and visceral Involvement (e.g. liver, bone marrow, or kidney).
Rifabutin is contraindicated in patients who have clinically significant rifabutin hypersensitivity or rifamycin hypersensitivity. Monitor patients receiving rifabutin therapy for signs and/or symptoms of hypersensitivity reactions. If these symptoms occur, administer supportive measures and discontinue rifabutin.
Consider pseudomembranous colitis in patients presenting with diarrhea after antibacterial use. Careful medical history is necessary as pseudomembranous colitis has been reported to occur over 2 months after the administration of antibacterial agents. Almost all antibacterial agents, including rifabutin, have been associated with pseudomembranous colitis or C. difficile-associated diarrhea (CDAD) which may range in severity from mild to life-threatening. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile.
In patients with severe renal impairment or renal failure, carefully monitor for rifabutin associated adverse events. A reduction in the dosage of rifabutin is recommended for patients with CrCl less than 30 mL/minute if toxicity is suspected.
In general, dose selection for a geriatric patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and concomitant disease or drug therapy. The federal Omnibus Budget Reconciliation Act (OBRA) regulates medication use in residents (e.g., geriatric adults) of long-term care facilities (LTCFs). According to OBRA, use of antibiotics should be limited to confirmed or suspected bacterial infections. Antibiotics are non-selective and may result in the eradication of beneficial microorganisms while promoting the emergence of undesired ones, causing secondary infections such as oral thrush, colitis, or vaginitis. Any antibiotic may cause diarrhea, nausea, vomiting, anorexia, and hypersensitivity reactions.
Rifabutin may produce a red-orange discoloration of body fluids. Contact lenses may become permanently stained due to rifabutin therapy.
Administration of rifabutin may result in laboratory test interference. Antimicrobials are known to suppress H. pylori; thus, ingestion of these agents within 4 weeks of performing diagnostic tests for H. pylori may lead to false negative results. At a minimum, instruct the patient to avoid the use of rifabutin in the 4 weeks prior to the test.
Do not administer rifabutin for Mycobacterium avium complex (MAC) prophylaxis to patients with active tuberculosis (TB). Evaluate patients who develop complaints consistent with active TB while on prophylaxis with rifabutin immediately, so that those with active disease may be given an effective combination regimen of anti-TB medications. Administration of rifabutin as a single agent to patients with active TB is likely to lead to the development of TB that is resistant both to rifabutin and rifampin.
There have been reports of serious rash or severe cutaneous adverse reactions (SCAR) associated with rifabutin use. If patients develop a skin rash, monitor them closely and discontinue rifabutin if lesions progress.
Use rifabutin during pregnancy only if the potential benefit justifies the potential risk to the fetus. There are no adequate and well-controlled studies of rifabutin use in pregnant women. No teratogenicity was observed in animal studies at doses about 6 to 13 times the recommended human daily dose based on body surface area comparisons. However, fetal skeletal anomalies were observed in rats and rabbits after administration of a dose approximately equivalent and a dose 5 times the recommended human daily dose, respectively. At 6 times the recommended human daily dose, a decrease in fetal viability was observed in rats.
There are no adequate and well-controlled studies of rifabutin use in breast-feeding women. It is not known if rifabutin is excreted into breast milk. Because many drugs are excreted in human breast milk and because of the risk for serious adverse reactions in breast-feeding infants, discontinue breast-feeding or rifabutin, taking into consideration the importance of the drug to the mother. Previous American Academy of Pediatrics (AAP) recommendations generally considered another rifamycin, rifampin, as compatible for use in lactating women.
Per the manufacturer, this drug has been shown to be active against most strains of the following microorganisms either in vitro and/or in clinical infections: Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium tuberculosis
NOTE: The safety and effectiveness in treating clinical infections due to organisms with in vitro data only have not been established in adequate and well-controlled clinical trials.
This drug may also have activity against the following microorganisms: Mycobacterium leprae
NOTE: Some organisms may not have been adequately studied during clinical trials; therefore, exclusion from this list does not necessarily negate the drug's activity against the organism.
For the treatment of Mycobacterium avium complex infection* (MAC):
-for the treatment of disseminated Mycobacterium avium complex (MAC)*:
NOTE: Rifabutin has been designated an orphan drug for this indication.
Oral dosage:
Adults: 150 to 450 mg PO once daily plus clarithromycin or azithromycin and ethambutol. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. Discontinue therapy with resolution of symptoms and reconstitution of cell-mediated immune function.
-for the treatment of Mycobacterium avium complex (MAC)* pulmonary disease:
Oral dosage:
Adults: 150 to 300 mg PO once daily plus clarithromycin or azithromycin and ethambutol with consideration of 3-times weekly amikacin or streptomycin for the first 2 to 3 months for patients with fibrocavitary MAC lung disease or severe nodular or bronchiectatic disease. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. Continue treatment until the patient is culture negative on therapy for 1 year. For macrolide-resistant MAC, consider 4-drug regimen including rifabutin plus isoniazid, ethambutol (for the first 2 months), and streptomycin or amikacin (for the first 3 to 6 months).
-for the treatment of Mycobacterium avium complex (MAC)* in persons with HIV:
Oral dosage:
Adults: 300 mg PO once daily plus clarithromycin or azithromycin and ethambutol. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. May consider addition of rifabutin as a third or fourth drug (or amikacin, streptomycin, levofloxacin, or moxifloxacin) for patients with high mycobacterial loads (more than 2 log CFU/mL of blood) or in the absence of effective antiretroviral therapy. Duration of treatment depends on clinical response but should continue for at least 12 months.
Adolescents: 300 mg PO once daily plus clarithromycin or azithromycin and ethambutol. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. May consider addition of rifabutin as a third or fourth drug (or amikacin, streptomycin, levofloxacin, or moxifloxacin) for patients with high mycobacterial loads (more than 2 log CFU/mL of blood) or in the absence of effective antiretroviral therapy. Duration of treatment depends on clinical response but should continue for at least 12 months.
Infants and Children: 10 to 20 mg/kg/dose (Max: 300 mg/dose) PO once daily plus clarithromycin or azithromycin and ethambutol for severe disease. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. If a fourth drug is needed for patients with more severe symptoms or disseminated disease, consider adding ciprofloxacin, levofloxacin, or amikacin. Duration of treatment depends on clinical response but should continue for at least 12 months.
For Mycobacterium avium complex (MAC) prophylaxis in persons with HIV:
-for primary Mycobacterium avium complex (MAC) prophylaxis:
Oral dosage:
Adults: 300 mg PO once daily as an alternative therapy. Consider 150 mg PO twice daily for patients with a propensity for gastrointestinal upset. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. Primary prophylaxis is only recommended for patients not on fully suppressive antiretroviral therapy (ART) with CD4 counts less than 50 cells/mm3 after ruling out disseminated MAC. Discontinue primary prophylaxis upon initiation of effective ART.
Adolescents*: 300 mg PO once daily as an alternative therapy. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. Primary prophylaxis is only recommended for patients not on fully suppressive antiretroviral therapy (ART) with CD4 counts less than 50 cells/mm3 after ruling out disseminated MAC. Discontinue primary prophylaxis upon initiation of effective ART.
Children 6 to 12 years*: 300 mg PO once daily as an alternative therapy. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. Primary prophylaxis is recommended in children 6 years and older with a CD4 count less than 50 cells/mm3. Primary prophylaxis may be discontinued after at least 6 months of ART and a CD4 count more than 100 cells/mm3 for at least 3 consecutive months. Restart primary prophylaxis if the CD4 count falls below these thresholds.
-for secondary Mycobacterium avium complex (MAC) prophylaxis in patients with disseminated disease, after treatment of the acute illness:
Oral dosage:
Adults: 300 mg PO once daily plus clarithromycin or azithromycin and ethambutol. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. May consider addition of rifabutin as a third or fourth drug (or amikacin, streptomycin, levofloxacin, or moxifloxacin) for patients with high mycobacterial loads (more than 2 log CFU/mL of blood) or in the absence of effective antiretroviral therapy. Consider discontinuing secondary prophylaxis in patients who have completed at least 12 months of MAC treatment, have no signs or symptoms of MAC, and have a sustained (more than 6 months) CD4 count more than 100 cells/mm3 in response to ART. Restart secondary prophylaxis if the CD4 count decreases to less than 100 cells/mm3.
Adolescents*: 300 mg PO once daily plus clarithromycin or azithromycin and ethambutol. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. May consider addition of rifabutin as a third or fourth drug (or amikacin, streptomycin, levofloxacin, or moxifloxacin) for patients with high mycobacterial loads (more than 2 log CFU/mL of blood) or in the absence of effective antiretroviral therapy. Consider discontinuing secondary prophylaxis in patients who have completed at least 12 months of MAC treatment, have no signs or symptoms of MAC, and have a sustained (more than 6 months) CD4 count more than 100 cells/mm3 in response to ART. Restart secondary prophylaxis if the CD4 count decreases to less than 100 cells/mm3.
Children 6 to 12 years*: 5 mg/kg/dose (Max: 300 mg/dose) PO once daily plus clarithromycin or azithromycin and ethambutol for children older than 5 years who received rifabutin as part of the initial treatment regimen. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. Consider discontinuing secondary prophylaxis in children who have received at least 12 months of MAC treatment, have no signs or symptoms of MAC, have been receiving stable antiretroviral therapy, and have a sustained (more than 6 months) CD4 count more than 100 cells/mm3. Restart secondary prophylaxis if the CD4 count falls below these thresholds.
For the treatment of drug-susceptible tuberculosis infection* as part of combination therapy:
Oral dosage:
Adults: 5 mg/kg/dose (Usual dose: 300 mg) PO once daily or 5 days/week. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. Daily dosing is defined as 5- or 7 days/week. Rifabutin is generally recommended throughout the intensive and continuation phases of treatment as first-line therapy; duration is dependent on the site of involvement.
Infants, Children, and Adolescents: 5 mg/kg/dose (Max: 300 mg/dose) PO given once daily or 5 days/week. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. Daily dosing is defined as 5- or 7 days/week. Rifabutin is generally recommended throughout the intensive and continuation phases of treatment as first-line therapy; duration is dependent on the site of involvement.
For the treatment of drug-resistant tuberculosis infection* as part of combination therapy:
Oral dosage:
Adults: 5 mg/kg/dose (Max: 600 mg) PO once daily. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions.
Infants, Children, and Adolescents: 5 to 10 mg/kg/dose (Max: 300 mg) PO once daily. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions.
For tuberculosis prophylaxis* or latent tuberculosis infection* (LTBI) as an alternative to isoniazid and rifampin regimens:
Oral dosage:
Adults: 5 mg/kg/dose (Usual dose: 300 mg/dose) PO once daily for 4 months. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. Rifabutin may be used in place of 4 months of daily rifampin when rifampin is contraindicated due to drug-drug interactions and isoniazid cannot be used. There are no data demonstrating its efficacy as monotherapy.
Infants, Children, and Adolescents: 5 mg/kg/dose (Max: 300 mg/dose) PO once daily once daily for 4 months. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. Rifabutin may be used in place of 4 months of daily rifampin when rifampin is contraindicated due to drug-drug interactions and isoniazid cannot be used. There are no data demonstrating its efficacy as monotherapy.
For Helicobacter pylori (H. pylori) eradication* as part of triple therapy:
Oral dosage:
Adults: 300 mg PO once daily in combination with amoxicillin and a proton pump inhibitor (PPI) for 10 days. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions.
Maximum Dosage Limits:
-Adults
300 mg/day PO is the FDA-approved maximum dosage; 450 mg/day PO has been used off-label.
-Geriatric
300 mg/day PO is the FDA-approved maximum dosage; 450 mg/day PO has been used off-label.
-Adolescents
Safety and efficacy have not been established; 5 mg/kg/day (Max: 300 mg/day) PO has been used off-label.
-Children
Safety and efficacy have not been established; 20 mg/kg/day (Max: 300 mg/day) PO has been used off-label.
-Infants
Safety and efficacy have not been established; 20 mg/kg/day PO has been used off-label.
-Neonates
Safety and efficacy have not been established.
Patients with Hepatic Impairment Dosing
Specific guidelines for dosage adjustments in hepatic impairment are not available; it appears that no dosage adjustments are needed.
Patients with Renal Impairment Dosing
CrCl 30 mL/minute or more: No dosage adjustment needed.
CrCl less than 30 mL/minute: Consider reducing the dose by 50% if toxicity is suspected.
Intermittent hemodialysis*
No dosage adjustment needed.
Peritoneal dialysis*
No dosage adjustment needed.
Continuous renal replacement therapy (CRRT)*
NOTE: Various CRRT modalities include continuous venovenous hemofiltration (CVVH), continuous venovenous hemodialysis (CVVHD), continuous venovenous hemodiafiltration (CVVHDF), continuous venovenous high-flux hemodialysis (CVVHFD), continuous arteriovenous hemofiltration (CAVH), continuous arteriovenous hemodialysis (CAVHD), and continuous arteriovenous hemodiafiltration (CAVHDF). Dosing should take into consideration patient-specific factors (e.g., intrinsic renal function), type of infection, the duration of renal replacement therapy, the effluent flow rate, and the replacement solution administered.
No dosage adjustment needed.
*non-FDA-approved indication
Abacavir; Lamivudine, 3TC; Zidovudine, ZDV: (Minor) Rifabutin may accelerate the metabolism of zidovudine. However the effectiveness of zidovudine against HIV does not appear to be altered and no dosage adjustments are required. The CDC currently considers the nucleoside reverse transcriptase inhibitors, including zidovudine, compatible for concomitant use with rifamycins, including rifampin, rifabutin and rifapentine.
Abemaciclib: (Major) Avoid coadministration of rifabutin with abemaciclib due to decreased exposure to abemaciclib and its active metabolites, which may lead to reduced efficacy. Abemaciclib is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Coadministration with other moderate CYP3A inducers is predicted to decrease the relative potency adjusted unbound AUC of abemaciclib plus its active metabolites (M2, M18, and M20) by 29% to 53%.
Abiraterone: (Moderate) Concomitant use of abiraterone with rifabutin may result in decreased serum concentrations of abiraterone. Abiraterone is a substrate of hepatic isoenzyme CYP3A4; rifabutin is a moderate inducer of this enzyme. Caution and close monitoring for decreased efficacy are advised if these drugs are used together.
Acetaminophen: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Aspirin, ASA; Caffeine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Aspirin: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Aspirin; Diphenhydramine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Caffeine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Caffeine; Dihydrocodeine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced. (Moderate) Monitor for reduced efficacy of dihydrocodeine and signs of opioid withdrawal if coadministration with rifamycins is necessary; consider increasing the dose of dihydrocodeine as needed. If the rifamycin is discontinued, consider a dose reduction of dihydrocodeine and frequently monitor for signs of respiratory depression and sedation. Rifamycins are inducers of CYP3A4, an isoenzyme partially responsible for the metabolism of dihydrocodeine. Concomitant use of dihydrocodeine with rifamycins can decrease dihydrocodeine levels, resulting in less metabolism by CYP2D6 and decreased dihydromorphine concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Acetaminophen; Caffeine; Pyrilamine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Chlorpheniramine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Chlorpheniramine; Dextromethorphan: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Chlorpheniramine; Phenylephrine : (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Codeine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced. (Moderate) Concomitant use of codeine with rifabutin can decrease codeine levels, resulting in less metabolism by CYP2D6 and decreased morphine concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor for reduced efficacy of codeine and signs of opioid withdrawal; consider increasing the dose of codeine as needed. If rifabutin is discontinued, consider a dose reduction of codeine and frequently monitor for signs or respiratory depression and sedation. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Rifabutin is a moderate CYP3A4 inducer.
Acetaminophen; Dextromethorphan: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Dextromethorphan; Doxylamine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Dextromethorphan; Phenylephrine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Dextromethorphan; Pseudoephedrine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Diphenhydramine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Guaifenesin; Phenylephrine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Hydrocodone: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced. (Moderate) Monitor for reduced efficacy of hydrocodone and signs of opioid withdrawal in patients who have developed physical dependence if coadministration with rifabutin is necessary; consider increasing the dose of hydrocodone as needed. It is recommended to avoid this combination when hydrocodone is being used for cough. If rifabutin is discontinued, consider a dose reduction of hydrocodone and frequently monitor for signs of respiratory depression and sedation. Hydrocodone is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Concomitant use can decrease hydrocodone levels.
Acetaminophen; Ibuprofen: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Oxycodone: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced. (Moderate) Monitor for reduced efficacy of oxycodone and signs of opioid withdrawal if coadministration with rifabutin is necessary; consider increasing the dose of oxycodone as needed. If rifabutin is discontinued, consider a dose reduction of oxycodone and frequently monitor for signs of respiratory depression and sedation. Oxycodone is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease oxycodone concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Acetaminophen; Pamabrom; Pyrilamine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Phenylephrine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Acetaminophen; Pseudoephedrine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Adagrasib: (Moderate) Monitor for an increase in rifabutin-related adverse reactions if coadministration with adagrasib is necessary; in some cases, the dose of rifabutin may need to be decreased. Rifabutin is a CYP3A substrate and adagrasib is a strong CYP3A inhibitor. Coadministration with CYP3A inhibitors may significantly increase the plasma concentration of rifabutin.
Alfentanil: (Moderate) Consider an increased dose of alfentanil and monitor for evidence of opioid withdrawal if coadministration with rifamycins is necessary. If the rifamycin is discontinued, consider reducing the alfentanil dosage and monitor for evidence of respiratory depression. Coadministration of CYP3A4 inducers like rifamycins with alfentanil, a CYP3A4 substrate, may decrease exposure to alfentanil resulting in decreased efficacy or onset of withdrawal symptoms in a patient who has developed physical dependence to alfentanil. Alfentanil plasma concentrations will increase once the inducer is stopped, which may increase or prolong the therapeutic and adverse effects, including serious respiratory depression.
Alprazolam: (Moderate) Rifabutin could induce the CYP3A4-mediated metabolism of oxidized benzodiazepines, such as alprazolam.
Aminosalicylate sodium, Aminosalicylic acid: (Moderate) Careful monitoring of hepatic function is recommended with the concurrent use of rifabutin and aminosalicylate sodium, aminosalicylic acid. Each drug has the potential to cause hepatotoxicity, and hepatotoxicity risk may be increased with concomitant use. These drugs may be used together for the treatment of active tuberculosis (TB) infection, and patients should also be assessed for additional risk factors for hepatotoxicity, such as other hepatotoxic drugs, alcohol use, and underlying hepatic disease. Any adverse event leading to hospitalization or death should be reported to local or state health departments as well as the FDA MedWatch program.
Amlodipine: (Moderate) Rifabutin may induce the CYP3A4 metabolism of calcium-channel blockers such as amlodipine and thereby reduce their oral bioavailability. The dosage requirements of amlodipine may be increased in patients receiving concurrent enzyme inducers.
Amlodipine; Atorvastatin: (Moderate) Rifabutin may induce the CYP3A4 metabolism of calcium-channel blockers such as amlodipine and thereby reduce their oral bioavailability. The dosage requirements of amlodipine may be increased in patients receiving concurrent enzyme inducers.
Amlodipine; Benazepril: (Moderate) Rifabutin may induce the CYP3A4 metabolism of calcium-channel blockers such as amlodipine and thereby reduce their oral bioavailability. The dosage requirements of amlodipine may be increased in patients receiving concurrent enzyme inducers.
Amlodipine; Celecoxib: (Moderate) Rifabutin may induce the CYP3A4 metabolism of calcium-channel blockers such as amlodipine and thereby reduce their oral bioavailability. The dosage requirements of amlodipine may be increased in patients receiving concurrent enzyme inducers.
Amlodipine; Olmesartan: (Moderate) Rifabutin may induce the CYP3A4 metabolism of calcium-channel blockers such as amlodipine and thereby reduce their oral bioavailability. The dosage requirements of amlodipine may be increased in patients receiving concurrent enzyme inducers.
Amlodipine; Valsartan: (Moderate) Rifabutin may induce the CYP3A4 metabolism of calcium-channel blockers such as amlodipine and thereby reduce their oral bioavailability. The dosage requirements of amlodipine may be increased in patients receiving concurrent enzyme inducers.
Amlodipine; Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Rifabutin may induce the CYP3A4 metabolism of calcium-channel blockers such as amlodipine and thereby reduce their oral bioavailability. The dosage requirements of amlodipine may be increased in patients receiving concurrent enzyme inducers.
Amoxicillin; Clarithromycin; Omeprazole: (Major) The combination of rifabutin and clarithromycin should be avoided. Clarithromycin is a substrate and inhibitor of CYP3A4, and rifabutin is a substrate and inducer of CYP3A4. The metabolism of rifabutin is inhibited by clarithromycin, possibly through inhibition of CYP3A4. Inhibition of rifabutin metabolism results in significant increases in rifabutin serum concentrations and adverse reactions. Also, rifabutin increases the metabolism of clarithromycin resulting in significant decreases in clarithromycin concentrations thereby reducing the antimicrobial efficacy of clarithromycin. As compared with the plasma concentration obtained with clarithromycin monotherapy, the clarithromycin plasma concentration was reduced by 63% when rifabutin 600 mg daily was coadministered. Specifically, as monotherapy, the mean serum clarithromycin concentration was 5.4 +/- 2.1 mcg/ml. The mean serum clarithromycin concentration was 2 +/- 1.5 mcg/ml when given in combination with rifabutin. The mean serum concentrations of 14-OH clarithromycin were similar between the two groups.
Apalutamide: (Moderate) Monitor for decreased efficacy of rifabutin and potential issues of resistance if coadministration with apalutamide is necessary. Rifabutin is a CYP3A4 substrate and apalutamide is a strong CYP3A4 inducer.
Aprepitant, Fosaprepitant: (Major) Use caution if rifabutin and aprepitant, fosaprepitant are used concurrently and monitor for a possible decrease in the efficacy of aprepitant as well as an increase in rifabutin-related adverse effects for several days after administration of a multi-day aprepitant regimen. Rifabutin is a CYP3A4 substrate. Aprepitant, when administered as a 3-day oral regimen (125 mg/80 mg/80 mg), is a moderate CYP3A4 inhibitor and inducer and may increase plasma concentrations of rifabutin. For example, a 5-day oral aprepitant regimen increased the AUC of another CYP3A4 substrate, midazolam (single dose), by 2.3-fold on day 1 and by 3.3-fold on day 5. After a 3-day oral aprepitant regimen, the AUC of midazolam (given on days 1, 4, 8, and 15) increased by 25% on day 4, and then decreased by 19% and 4% on days 8 and 15, respectively. As a single 125 mg or 40 mg oral dose, the inhibitory effect of aprepitant on CYP3A4 is weak, with the AUC of midazolam increased by 1.5-fold and 1.2-fold, respectively. After administration, fosaprepitant is rapidly converted to aprepitant and shares many of the same drug interactions. However, as a single 150 mg intravenous dose, fosaprepitant only weakly inhibits CYP3A4 for a duration of 2 days; there is no evidence of CYP3A4 induction. Fosaprepitant 150 mg IV as a single dose increased the AUC of midazolam (given on days 1 and 4) by approximately 1.8-fold on day 1; there was no effect on day 4. Less than a 2-fold increase in the midazolam AUC is not considered clinically important. Additionally, Rifabutin is a moderate CYP3A4 inducer and aprepitant is a CYP3A4 substrate. When a single dose of aprepitant (375 mg, or 3 times the maximum recommended dose) was administered on day 9 of a 14-day rifampin regimen (a strong CYP3A4 inducer), the AUC of aprepitant decreased approximately 11-fold and the mean terminal half-life decreased by 3-fold. The manufacturer of aprepitant recommends avoidance of administration with strong CYP3A4 inducers, but does not provide guidance for weak-to-moderate inducers.
Aripiprazole: (Moderate) Because aripiprazole is partially metabolized by CYP3A4, caution is advisable during coadministration of a CYP3A4 inducer, such as rifabutin. If these agents are used in combination, the patient should be carefully monitored for a decrease in aripiprazole efficacy. A dose adjustment of aripiprazole may be needed. Avoid concurrent use of Abilify Maintena with a CYP3A4 inducer when the combined treatment period exceeds 14 days because aripiprazole blood concentrations decline and may become suboptimal. There are no dosing recommendations for Aristada or Aristada Initio during use of a mild to moderate CYP3A4 inducer.
Armodafinil: (Moderate) Armodafinil is partially metabolized via CYP3A4/5 isoenzymes. Drugs that exhibit significant induction of the CYP3A4 isoenzyme, such as rifabutin, may potentially increase the metabolism of armodafinil. Decreased serum levels of armodafinil could potentially result in decreased efficacy of the drug.
Artemether; Lumefantrine: (Major) Rifabutin is a substrate/inducer and both components of artemether; lumefantrine are substrates of the CYP3A4 isoenzyme; therefore, coadministration may lead to decreased artemether; lumefantrine concentrations. Concomitant use warrants caution due to a possible reduction in antimalarial activity.
Aspirin, ASA; Caffeine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Aspirin, ASA; Carisoprodol; Codeine: (Moderate) Concomitant use of codeine with rifabutin can decrease codeine levels, resulting in less metabolism by CYP2D6 and decreased morphine concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor for reduced efficacy of codeine and signs of opioid withdrawal; consider increasing the dose of codeine as needed. If rifabutin is discontinued, consider a dose reduction of codeine and frequently monitor for signs or respiratory depression and sedation. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Rifabutin is a moderate CYP3A4 inducer.
Aspirin, ASA; Oxycodone: (Moderate) Monitor for reduced efficacy of oxycodone and signs of opioid withdrawal if coadministration with rifabutin is necessary; consider increasing the dose of oxycodone as needed. If rifabutin is discontinued, consider a dose reduction of oxycodone and frequently monitor for signs of respiratory depression and sedation. Oxycodone is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease oxycodone concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Atazanavir: (Major) Reduce the rifabutin dose to 150 mg PO once daily and monitor for adverse effects, such as uveitis and neutropenia, if concomitant use with atazanavir is necessary. Avoid concurrent use of rifabutin and atazanavir boosted with cobicistat. Although the FDA-approved labeling recommends reducing the rifabutin dose by at least 75% (to a maximum 150 mg every other day or 3 times per week), lower rifabutin exposure has been reported in persons living with HIV than in healthy subjects and acquired rifamycin resistance has been reported in these persons receiving 3 times weekly regimens. Monitor response and consider therapeutic drug monitoring (TDM) when rifabutin is used with atazanavir boosted with ritonavir and adjust dose accordingly. Rifabutin is a CYP3A substrate and atazanavir is a strong CYP3A inhibitor. Coadministration with atazanavir/ritonavir increased the AUC of rifabutin by approximately 110%.
Atazanavir; Cobicistat: (Major) Avoid concurrent use of rifabutin and cobicistat-containing antiretroviral regimens. Concomitant use may decrease cobicistat exposure which may reduce its efficacy and increase rifabutin exposure and risk of adverse effects. Rifabutin is a CYP3A substrate and moderate CYP3A inducer; cobicistat is a CYP3A substrate and strong CYP3A inhibitor. (Major) Reduce the rifabutin dose to 150 mg PO once daily and monitor for adverse effects, such as uveitis and neutropenia, if concomitant use with atazanavir is necessary. Avoid concurrent use of rifabutin and atazanavir boosted with cobicistat. Although the FDA-approved labeling recommends reducing the rifabutin dose by at least 75% (to a maximum 150 mg every other day or 3 times per week), lower rifabutin exposure has been reported in persons living with HIV than in healthy subjects and acquired rifamycin resistance has been reported in these persons receiving 3 times weekly regimens. Monitor response and consider therapeutic drug monitoring (TDM) when rifabutin is used with atazanavir boosted with ritonavir and adjust dose accordingly. Rifabutin is a CYP3A substrate and atazanavir is a strong CYP3A inhibitor. Coadministration with atazanavir/ritonavir increased the AUC of rifabutin by approximately 110%.
Atogepant: (Major) Avoid use of atogepant and rifabutin when atogepant is used for chronic migraine. Use an atogepant dose of 30 or 60 mg PO once daily for episodic migraine if coadministered with rifabutin. Concurrent use may decrease atogepant exposure and reduce efficacy. Atogepant is a CYP3A substrate and rifabutin is a moderate CYP3A inducer.
Atovaquone: (Major) The administration of rifabutin with atovaquone is not recommended. Taking these drugs together reduces the average steady-state plasma concentrations of atovaquone and rifabutin by 34% and 19%, respectively. Dose adjustments have not been established. If these drugs are given together, instruct patient to take atovaquone with a fatty meal and monitor for decreased atovaquone efficacy.
Atovaquone; Proguanil: (Major) The administration of rifabutin with atovaquone is not recommended. Taking these drugs together reduces the average steady-state plasma concentrations of atovaquone and rifabutin by 34% and 19%, respectively. Dose adjustments have not been established. If these drugs are given together, instruct patient to take atovaquone with a fatty meal and monitor for decreased atovaquone efficacy.
Avacopan: (Major) Avoid concomitant use of avacopan and rifabutin due to the risk of decreased avacopan exposure which may reduce its efficacy. Avacopan is a CYP3A substrate and rifabutin is a moderate CYP3A inducer.
Avanafil: (Minor) Avanafil is primarily metabolized by CYP3A4, and although no studies have been performed, concomitant administration of CYP3A4 inducers, such as rifabutin, may decrease avanafil plasma levels. Concomitant use is not recommended.
Avapritinib: (Major) Avoid coadministration of avapritinib with rifabutin due to the risk of decreased avapritinib efficacy. Avapritinib is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Coadministration with another moderate CYP3A4 inducer is predicted to decrease the AUC and Cmax of avapritinib by 62% and 55%, respectively.
Axitinib: (Major) Avoid coadministration of axitinib with rifabutin due to the risk of decreased efficacy of axitinib. Selection of a concomitant medication with no or minimal CYP3A4 induction potential is recommended. Axitinib is a CYP3A4/5 substrate and rifabutin is a CYP3A4 inducer. Coadministration with a strong CYP3A4/5 inducer significantly decreased the plasma exposure of axitinib in healthy volunteers.
Bacillus Calmette-Guerin Vaccine, BCG: (Major) Urinary concentrations of rifabutin could interfere with the therapeutic effectiveness of BCG. Postpone instillation of BCG if the patient is receiving antibiotics.
Bedaquiline: (Major) Avoid concurrent use of bedaquiline with rifamycins (e.g., rifampin, rifapentine, and rifabutin). Rifamycins may induce the CYP3A4 metabolism of bedaquiline, resulting in decreased bedaquiline systemic exposure (AUC) and possibly reduced therapeutic effect. One study found bedaquiline AUC decreased by 52% when administered concurrently with rifampin 600 mg PO daily for 21 days.
Benzhydrocodone; Acetaminophen: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced. (Moderate) Concurrent use of benzhydrocodone with rifabutin may decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to opioid agonists. If concomitant use is necessary, consider increasing the benzhydrocodone dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal. Discontinuation of rifabutin may increase the risk of increased opioid-related adverse reactions, such as fatal respiratory depression. If rifabutin is discontinued, consider a benzhydrocodone dosage reduction and monitor patients for respiratory depression and sedation at frequent intervals. Benzhydrocodone is a prodrug of hydrocodone. Rifabutin is an inducer of CYP3A4, an isoenzyme partially responsible for the metabolism of hydrocodone.
Bictegravir; Emtricitabine; Tenofovir Alafenamide: (Major) Coadministration is not recommended. Concurrent use may result in significant decreases in the plasma concentrations of tenofovir alafenamide, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. (Major) Concomitant use of bictegravir and rifabutin is not recommended as coadministration may result in decreased bictegravir plasma concentrations, which may result in the loss of therapeutic efficacy and development of resistance. Bictegravir is a substrate of CYP3A4; rifabutin is an inducer of CYP3A4.
Bortezomib: (Minor) Agents that induce CYP3A4, such as rifabutin, may decrease the exposure to bortezomib and possibly decrease the efficacy of the drug; however, bortezomib is also metabolized by other CYP isoenzymes. Therefore, the clinical significance of concurrent administration of bortezomib with CYP3A4 inducers is not known.
Brigatinib: (Major) Avoid coadministration of brigatinib with rifabutin due to decreased plasma exposure to brigatinib which may result in decreased efficacy. If concomitant use is unavoidable, after 7 days of concomitant treatment with rifabutin, increase the dose of brigatinib as tolerated in 30 mg increments to a maximum of twice the original brigatinib dose. After discontinuation of rifabutin, resume the brigatinib dose that was tolerated prior to initiation of rifabutin. Brigatinib is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Coadministration with a moderate CYP3A inducer is predicted to decrease the AUC of brigatinib by approximately 50%.
Bromocriptine: (Moderate) Caution and close monitoring are advised if bromocriptine and rifabutin are used together. Concurrent use may decrease the plasma concentrations of bromocriptine resulting in loss of efficacy. Bromocriptine is extensively metabolized by the liver via CYP3A4; rifabutin is a moderate inducer of CYP3A4.
Bupivacaine; Lidocaine: (Moderate) Concomitant use of systemic lidocaine and rifabutin may decrease lidocaine plasma concentrations. Higher lidocaine doses may be required; titrate to effect. Lidocaine is a CYP3A4 and CYP1A2 substrate; rifabutin induces CYP3A4.
Buprenorphine: (Moderate) Monitor for decreased efficacy of buprenorphine, and potentially the onset of a withdrawal syndrome in patients who have developed physical dependence to buprenorphine, if coadministration with rifamycins is necessary; consider increasing the dose of buprenorphine until stable drug effects are achieved. If the rifamycin is discontinued, consider a buprenorphine dose reduction and monitor for signs of respiratory depression. Buprenorphine is a CYP3A4 substrate and rifamycins are CYP3A4 inducers.
Buprenorphine; Naloxone: (Moderate) Monitor for decreased efficacy of buprenorphine, and potentially the onset of a withdrawal syndrome in patients who have developed physical dependence to buprenorphine, if coadministration with rifamycins is necessary; consider increasing the dose of buprenorphine until stable drug effects are achieved. If the rifamycin is discontinued, consider a buprenorphine dose reduction and monitor for signs of respiratory depression. Buprenorphine is a CYP3A4 substrate and rifamycins are CYP3A4 inducers.
Butalbital; Acetaminophen: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Butalbital; Acetaminophen; Caffeine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Butalbital; Acetaminophen; Caffeine; Codeine: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced. (Moderate) Concomitant use of codeine with rifabutin can decrease codeine levels, resulting in less metabolism by CYP2D6 and decreased morphine concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor for reduced efficacy of codeine and signs of opioid withdrawal; consider increasing the dose of codeine as needed. If rifabutin is discontinued, consider a dose reduction of codeine and frequently monitor for signs or respiratory depression and sedation. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Rifabutin is a moderate CYP3A4 inducer.
Butalbital; Aspirin; Caffeine; Codeine: (Moderate) Concomitant use of codeine with rifabutin can decrease codeine levels, resulting in less metabolism by CYP2D6 and decreased morphine concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor for reduced efficacy of codeine and signs of opioid withdrawal; consider increasing the dose of codeine as needed. If rifabutin is discontinued, consider a dose reduction of codeine and frequently monitor for signs or respiratory depression and sedation. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Rifabutin is a moderate CYP3A4 inducer.
Cabotegravir: (Major) Coadministration of rifabutin and cabotegravir; rilpivirine injection is contraindicated due to the potential for significant decreases in the plasma concentrations of cabotegravir and rilpivirine, which may result in potential loss of virologic response and development of resistance. Rifabutin may be coadministered with cabotegravir extended-release injection; however, dosage adjustments are needed. When rifabutin is started before or concomitantly with the first initiation injection of cabotegravir injection, the recommended dosing of cabotegravir injection is one 600-mg injection, followed 2 weeks later by a second 600-mg initiation injection and monthly thereafter while on rifabutin. When rifabutin is started at the time of the second initiation injection or later, the recommended dosing schedule of cabotegravir injection is 600 mg monthly while on rifabutin. After stopping rifabutin, the recommended dosing schedule of cabotegravir injection is 600 mg every 2 months. Cabotegravir is a substrate for UGT1A1 and UGT1A9; rifabutin is an inducer of UGT. Coadministration with rifabutin decreased cabotegravir exposure by 33%. Rifabutin may be coadministered with oral cabotegravir monotherapy.
Cabotegravir; Rilpivirine: (Major) Coadministration of rifabutin and cabotegravir; rilpivirine injection is contraindicated due to the potential for significant decreases in the plasma concentrations of cabotegravir and rilpivirine, which may result in potential loss of virologic response and development of resistance. Rifabutin may be coadministered with cabotegravir extended-release injection; however, dosage adjustments are needed. When rifabutin is started before or concomitantly with the first initiation injection of cabotegravir injection, the recommended dosing of cabotegravir injection is one 600-mg injection, followed 2 weeks later by a second 600-mg initiation injection and monthly thereafter while on rifabutin. When rifabutin is started at the time of the second initiation injection or later, the recommended dosing schedule of cabotegravir injection is 600 mg monthly while on rifabutin. After stopping rifabutin, the recommended dosing schedule of cabotegravir injection is 600 mg every 2 months. Cabotegravir is a substrate for UGT1A1 and UGT1A9; rifabutin is an inducer of UGT. Coadministration with rifabutin decreased cabotegravir exposure by 33%. Rifabutin may be coadministered with oral cabotegravir monotherapy. (Major) Increase the dose of rilpivirine to 50 mg PO once daily when coadministered with rifabutin. When rifabutin coadministration is stopped, decrease the rilpivirine dose to 25 mg PO once daily. Coadministration of rilpivirine with rifabutin may result in decreased plasma concentrations of rilpivirine, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Rilpivirine is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer.
Cabozantinib: (Major) Avoid coadministration of cabozantinib with rifabutin due to the risk of decreased cabozantinib exposure which could affect efficacy. If concomitant use is unavoidable, increase the dose of cabozantinib. For patients taking cabozantinib tablets, increase the dose of cabozantinib by 20 mg (e.g., 60 mg/day to 80 mg/day; 40 mg/day to 60 mg/day); the daily dose should not exceed 80 mg. For patients taking cabozantinib capsules, increase the dose of cabozantinib by 40 mg (e.g., 140 mg/day to 180 mg/day or 100 mg/day to 140 mg/day); the daily dose should not exceed 180 mg. Resume the cabozantinib dose that was used prior to initiating treatment with rifabutin 2 to 3 days after discontinuation of rifabutin. Cabozantinib is a CYP3A4 substrate and rifabutin is a CYP3A4 inducer.
Capivasertib: (Major) Avoid coadministration of capivasertib with rifabutin due to decreased capivasertib exposure and risk of decreased efficacy. Capivasertib is a CYP3A substrate; rifabutin is a moderate CYP3A inducer. Coadministration of another moderate CYP3A inducer is predicted to decrease the capivasertib overall exposure by 60%.
Capmatinib: (Major) Avoid coadministration of capmatinib and rifabutin due to the risk of decreased capmatinib exposure, which may reduce its efficacy. Capmatinib is a CYP3A substrate and rifabutin is a moderate CYP3A4 inducer. Coadministration with another moderate CYP3A4 inducer decreased capmatinib exposure by 44%.
Capreomycin: (Moderate) Adverse hepatic effects have been associated with capreomycin, especially with concurrent use of other antituberculosis drugs known to alter hepatic function. Theoretically, coadministration of capreomycin and any of the rifamycins could increase the risk of hepatotoxicity. Monitor patients for changes in liver function if these drugs are coadministered.
Carbamazepine: (Moderate) Inducers of the hepatic CYP3A4 isoenzyme, such as rifabutin, can increase the rate of carbamazepine metabolism, leading to subtherapeutic carbamazepine plasma concentrations.
Cariprazine: (Major) Cariprazine and its active metabolites are extensively metabolized by CYP3A4. Concurrent use of cariprazine with CYP3A4 inducers, such as rifabutin or rifampin, has not been evaluated and is not recommended because the net effect on active drug and metabolites is unclear.
Carvedilol: (Moderate) Serum concentrations of carvedilol may be decreased if coadministered with rifabutin. Rifabutin is a known hepatic enzyme inducer, thus, it is not possible to stagger the administration times to avoid this interaction.
Caspofungin: (Moderate) Consider dosing caspofungin as 70 mg IV once daily in adult patients and 70 mg/m2 IV once daily (Max: 70 mg/day) in pediatric patients receiving rifabutin. Coadministration of CYP450 enzyme inducers, such as rifabutin, with caspofungin may reduce the plasma concentrations of caspofungin.
Ceritinib: (Moderate) Monitor for an increase in rifabutin-related adverse reactions if coadministration with ceritinib is necessary; a dosage adjustment may be necessary. Ceritinib is a strong CYP3A4 inhibitor and rifabutin is primarily metabolized by CYP3A4. Concomitant medications that competitively inhibit the CYP3A activity may increase plasma concentrations of rifabutin.
Chlordiazepoxide: (Moderate) Rifabutin is a hepatic inducer and can theoretically increase the clearance of benzodiazpines metabolized by oxidative metabolism, including chlordiazepoxide, leading to lower benzodiazepine concentrations.
Chlordiazepoxide; Amitriptyline: (Moderate) Rifabutin is a hepatic inducer and can theoretically increase the clearance of benzodiazpines metabolized by oxidative metabolism, including chlordiazepoxide, leading to lower benzodiazepine concentrations.
Chlordiazepoxide; Clidinium: (Moderate) Rifabutin is a hepatic inducer and can theoretically increase the clearance of benzodiazpines metabolized by oxidative metabolism, including chlordiazepoxide, leading to lower benzodiazepine concentrations.
Chlorpheniramine; Codeine: (Moderate) Concomitant use of codeine with rifabutin can decrease codeine levels, resulting in less metabolism by CYP2D6 and decreased morphine concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor for reduced efficacy of codeine and signs of opioid withdrawal; consider increasing the dose of codeine as needed. If rifabutin is discontinued, consider a dose reduction of codeine and frequently monitor for signs or respiratory depression and sedation. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Rifabutin is a moderate CYP3A4 inducer.
Chlorpheniramine; Hydrocodone: (Moderate) Monitor for reduced efficacy of hydrocodone and signs of opioid withdrawal in patients who have developed physical dependence if coadministration with rifabutin is necessary; consider increasing the dose of hydrocodone as needed. It is recommended to avoid this combination when hydrocodone is being used for cough. If rifabutin is discontinued, consider a dose reduction of hydrocodone and frequently monitor for signs of respiratory depression and sedation. Hydrocodone is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Concomitant use can decrease hydrocodone levels.
Chlorpromazine: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin.
Cisapride: (Moderate) Cisapride is metabolized by the hepatic cytochrome P450 enzyme system, specifically the CYP3A4 isoenzyme. Inducers of CYP3A4, such as rifabutin, may increase the clearance of cisapride.
Citalopram: (Moderate) Citalopram is metabolized by CYP2C19 and CYP3A4. Rifabutin can induce the metabolism of various CYP 450 isoenzymes, including those involved in citalopram metabolism. The possibility of an increase in the clearance of citalopram should be considered if coadministered with rifabutin.
Clarithromycin: (Major) The combination of rifabutin and clarithromycin should be avoided. Clarithromycin is a substrate and inhibitor of CYP3A4, and rifabutin is a substrate and inducer of CYP3A4. The metabolism of rifabutin is inhibited by clarithromycin, possibly through inhibition of CYP3A4. Inhibition of rifabutin metabolism results in significant increases in rifabutin serum concentrations and adverse reactions. Also, rifabutin increases the metabolism of clarithromycin resulting in significant decreases in clarithromycin concentrations thereby reducing the antimicrobial efficacy of clarithromycin. As compared with the plasma concentration obtained with clarithromycin monotherapy, the clarithromycin plasma concentration was reduced by 63% when rifabutin 600 mg daily was coadministered. Specifically, as monotherapy, the mean serum clarithromycin concentration was 5.4 +/- 2.1 mcg/ml. The mean serum clarithromycin concentration was 2 +/- 1.5 mcg/ml when given in combination with rifabutin. The mean serum concentrations of 14-OH clarithromycin were similar between the two groups.
Clonazepam: (Moderate) Rifabutin is a hepatic inducer and can theoretically increase the clearance of benzodiazepines metabolized by oxidative metabolism, such as clonazepam, leading to lower benzodiazepine concentrations.
Clorazepate: (Moderate) Rifabutin is a hepatic inducers and can theoretically increase the clearance of benzodiazpines metabolized by oxidative metabolism, such as clorazepate, leading to lower benzodiazepine concentrations.
Clozapine: (Moderate) Monitor for loss of clozapine effectiveness if coadministered with rifabutin. Consideration should be given to increasing the clozapine dose if necessary. When rifabutin is discontinued, reduce the clozapine dose based on clinical response. Clozapine is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer.
Cobicistat: (Major) Avoid concurrent use of rifabutin and cobicistat-containing antiretroviral regimens. Concomitant use may decrease cobicistat exposure which may reduce its efficacy and increase rifabutin exposure and risk of adverse effects. Rifabutin is a CYP3A substrate and moderate CYP3A inducer; cobicistat is a CYP3A substrate and strong CYP3A inhibitor.
Cobimetinib: (Major) Avoid the concurrent use of cobimetinib with rifabutin due to decreased cobimetinib efficacy. Cobimetinib is a CYP3A substrate in vitro, and rifabutin is a moderate inducer of CYP3A. Based on simulations, cobimetinib exposure would decrease by 73% when coadministered with a moderate CYP3A inducer.
Codeine: (Moderate) Concomitant use of codeine with rifabutin can decrease codeine levels, resulting in less metabolism by CYP2D6 and decreased morphine concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor for reduced efficacy of codeine and signs of opioid withdrawal; consider increasing the dose of codeine as needed. If rifabutin is discontinued, consider a dose reduction of codeine and frequently monitor for signs or respiratory depression and sedation. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Rifabutin is a moderate CYP3A4 inducer.
Codeine; Guaifenesin: (Moderate) Concomitant use of codeine with rifabutin can decrease codeine levels, resulting in less metabolism by CYP2D6 and decreased morphine concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor for reduced efficacy of codeine and signs of opioid withdrawal; consider increasing the dose of codeine as needed. If rifabutin is discontinued, consider a dose reduction of codeine and frequently monitor for signs or respiratory depression and sedation. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Rifabutin is a moderate CYP3A4 inducer.
Codeine; Guaifenesin; Pseudoephedrine: (Moderate) Concomitant use of codeine with rifabutin can decrease codeine levels, resulting in less metabolism by CYP2D6 and decreased morphine concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor for reduced efficacy of codeine and signs of opioid withdrawal; consider increasing the dose of codeine as needed. If rifabutin is discontinued, consider a dose reduction of codeine and frequently monitor for signs or respiratory depression and sedation. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Rifabutin is a moderate CYP3A4 inducer.
Codeine; Phenylephrine; Promethazine: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin. (Moderate) Concomitant use of codeine with rifabutin can decrease codeine levels, resulting in less metabolism by CYP2D6 and decreased morphine concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor for reduced efficacy of codeine and signs of opioid withdrawal; consider increasing the dose of codeine as needed. If rifabutin is discontinued, consider a dose reduction of codeine and frequently monitor for signs or respiratory depression and sedation. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Rifabutin is a moderate CYP3A4 inducer.
Codeine; Promethazine: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin. (Moderate) Concomitant use of codeine with rifabutin can decrease codeine levels, resulting in less metabolism by CYP2D6 and decreased morphine concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor for reduced efficacy of codeine and signs of opioid withdrawal; consider increasing the dose of codeine as needed. If rifabutin is discontinued, consider a dose reduction of codeine and frequently monitor for signs or respiratory depression and sedation. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Rifabutin is a moderate CYP3A4 inducer.
Conjugated Estrogens: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Conjugated Estrogens; Bazedoxifene: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Conjugated Estrogens; Medroxyprogesterone: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Cyclosporine: (Moderate) Closely monitor cyclosporine concentrations and adjust the dose of cyclosporine as appropriate if coadministration with rifamycins is necessary. Concurrent use may decrease cyclosporine exposure resulting in decreased efficacy. Cyclosporine is extensively metabolized by CYP3A4 and has a narrow therapeutic index; rifamycins are CYP3A4 inducers.
Daclatasvir: (Major) The dose of daclatasvir, a CYP3A4 substrate, must be increased to 90 mg PO once daily when administered in combination with moderate CYP3A4 inducers, such as rifabutin. Taking these drugs together may decrease daclatasvir serum concentrations, potentially resulting in reduced antiviral efficacy and antimicrobial resistance.
Dapsone: (Moderate) Closely monitor for a reduction in dapsone efficacy and signs of hemolytic anemia if coadministration with rifabutin is necessary. Dapsone is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Coadministration may decrease plasma concentrations of dapsone and increase the formation of dapsone hydroxylamine (a metabolite associated with hemolysis). In a study of 16 HIV-infected patients, rifabutin decreased dapsone exposure by 27% to 40%.
Daridorexant: (Major) Avoid concomitant use of daridorexant and rifabutin. Coadministration may decrease daridorexant exposure which may reduce its efficacy. Daridorexant is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Concomitant use of another moderate CYP3A inducer decreased daridorexant overall exposure by over 50%.
Darunavir: (Major) Reduce the rifabutin dose to 150 mg PO once daily and monitor for adverse effects, such as uveitis and neutropenia, if concomitant use with darunavir is necessary. Avoid concurrent use of rifabutin and darunavir boosted with cobicistat. Although the FDA-approved labeling recommends reducing the rifabutin dose by at least 75% (to a maximum 150 mg every other day or 3 times per week), lower rifabutin exposure has been reported in persons living with HIV than in healthy subjects and acquired rifamycin resistance has been reported in these persons receiving 3 times weekly regimens. Monitor response and consider therapeutic drug monitoring (TDM) when rifabutin is used with darunavir boosted with ritonavir and adjust dose accordingly. Rifabutin is a CYP3A substrate and darunavir is a strong CYP3A inhibitor. Coadministration with darunavir increased the AUC of the active metabolite of rifabutin by 881%.
Darunavir; Cobicistat: (Major) Avoid concurrent use of rifabutin and cobicistat-containing antiretroviral regimens. Concomitant use may decrease cobicistat exposure which may reduce its efficacy and increase rifabutin exposure and risk of adverse effects. Rifabutin is a CYP3A substrate and moderate CYP3A inducer; cobicistat is a CYP3A substrate and strong CYP3A inhibitor. (Major) Reduce the rifabutin dose to 150 mg PO once daily and monitor for adverse effects, such as uveitis and neutropenia, if concomitant use with darunavir is necessary. Avoid concurrent use of rifabutin and darunavir boosted with cobicistat. Although the FDA-approved labeling recommends reducing the rifabutin dose by at least 75% (to a maximum 150 mg every other day or 3 times per week), lower rifabutin exposure has been reported in persons living with HIV than in healthy subjects and acquired rifamycin resistance has been reported in these persons receiving 3 times weekly regimens. Monitor response and consider therapeutic drug monitoring (TDM) when rifabutin is used with darunavir boosted with ritonavir and adjust dose accordingly. Rifabutin is a CYP3A substrate and darunavir is a strong CYP3A inhibitor. Coadministration with darunavir increased the AUC of the active metabolite of rifabutin by 881%.
Darunavir; Cobicistat; Emtricitabine; Tenofovir alafenamide: (Major) Avoid concurrent use of rifabutin and cobicistat-containing antiretroviral regimens. Concomitant use may decrease cobicistat exposure which may reduce its efficacy and increase rifabutin exposure and risk of adverse effects. Rifabutin is a CYP3A substrate and moderate CYP3A inducer; cobicistat is a CYP3A substrate and strong CYP3A inhibitor. (Major) Coadministration is not recommended. Concurrent use may result in significant decreases in the plasma concentrations of tenofovir alafenamide, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. (Major) Reduce the rifabutin dose to 150 mg PO once daily and monitor for adverse effects, such as uveitis and neutropenia, if concomitant use with darunavir is necessary. Avoid concurrent use of rifabutin and darunavir boosted with cobicistat. Although the FDA-approved labeling recommends reducing the rifabutin dose by at least 75% (to a maximum 150 mg every other day or 3 times per week), lower rifabutin exposure has been reported in persons living with HIV than in healthy subjects and acquired rifamycin resistance has been reported in these persons receiving 3 times weekly regimens. Monitor response and consider therapeutic drug monitoring (TDM) when rifabutin is used with darunavir boosted with ritonavir and adjust dose accordingly. Rifabutin is a CYP3A substrate and darunavir is a strong CYP3A inhibitor. Coadministration with darunavir increased the AUC of the active metabolite of rifabutin by 881%.
Deflazacort: (Major) Avoid concomitant use of deflazacort and rifabutin. Concurrent use may significantly decrease concentrations of 21-desDFZ, the active metabolite of deflazacort, resulting in loss of efficacy. Deflazacort is a CYP3A4 substrate; rifabutin is a moderate inducer of CYP3A4. Administration of deflazacort with multiple doses of rifampin (a strong CYP3A4 inducer) resulted in geometric mean exposures that were approximately 95% lower compared to administration alone.
Delavirdine: (Contraindicated) The coadministration of rifabutin and delavirdine is contraindicated. Concurrent administration results in a 230% increase in rifabutin AUC. However, rifabutin significantly decreases delavirdine plasma concentrations. Clinical pharmacokinetic studies have shown an 82% reduction in delavirdine AUC when rifabutin was given concurrently.
Desogestrel; Ethinyl Estradiol: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Dextromethorphan; Quinidine: (Moderate) Rifabutin is an inducer of the cytochrome P-450 hepatic enzyme system and can reduce the plasma concentrations and possibly the efficacy of quinidine.
Diazepam: (Moderate) Rifabutin induces hepatic isoenzymes CYP3A4 and CYP2C8/9. Drugs metabolized by CYP3A4 and CYP2C8/9, such as diazepam, may require dosage adjustments when administered concurrently with rifabutin.
Dienogest; Estradiol valerate: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Diltiazem: (Moderate) Diltiazem is a CYP3A4 substrate and inhibitor. Rifabutin is a CYP3A4 substrate and inducer. Coadministration of these drugs could lead to a complex interaction. Significant decreases in diltiazem concentrations could be seen, and significant increases in rifabutin concentrations could be seen. When possible, avoid coadministration of these drugs and consider alternative therapy. When an alternative therapy is not possible, patients should be monitored for the desired cardiovascular effects on heart rate, chest pain, or blood pressure, as well as associated rifabutin side effects.
Disopyramide: (Moderate) Hepatic microsomal enzyme-inducing agents, such as rifabutin, have the potential to accelerate the hepatic metabolism of disopyramide, a CYP3A4 substrate. Patients should be monitored for loss of disopyramide activity if rifabutin is added.
Dolutegravir; Rilpivirine: (Major) Increase the dose of rilpivirine to 50 mg PO once daily when coadministered with rifabutin. When rifabutin coadministration is stopped, decrease the rilpivirine dose to 25 mg PO once daily. Coadministration of rilpivirine with rifabutin may result in decreased plasma concentrations of rilpivirine, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Rilpivirine is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer.
Doravirine: (Major) Increase the doravirine dose to 100 mg PO twice daily (approximately 12 hours apart) if coadministered with rifabutin. Concurrent use decreases doravirine exposure, resulting in potential loss of virologic control. Doravirine is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer.
Doravirine; Lamivudine; Tenofovir disoproxil fumarate: (Major) Increase the doravirine dose to 100 mg PO twice daily (approximately 12 hours apart) if coadministered with rifabutin. Concurrent use decreases doravirine exposure, resulting in potential loss of virologic control. Doravirine is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer.
Doxercalciferol: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as rifabutin, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Doxorubicin Liposomal: (Major) Rifabutin is a CYP3A4 inducer and doxorubicin is a major substrate of CYP3A4. Inducers of CYP3A4 may decrease the concentration of doxorubicin and compromise the efficacy of chemotherapy. Avoid coadministration of rifabutin and doxorubicin if possible. If not possible, monitor doxorubicin closely for efficacy.
Doxorubicin: (Major) Rifabutin is a CYP3A4 inducer and doxorubicin is a major substrate of CYP3A4. Inducers of CYP3A4 may decrease the concentration of doxorubicin and compromise the efficacy of chemotherapy. Avoid coadministration of rifabutin and doxorubicin if possible. If not possible, monitor doxorubicin closely for efficacy.
Dronabinol: (Moderate) Use caution if coadministration of dronabinol with rifabutin is necessary, and monitor for a decrease in the efficacy of dronabinol. Concomitant use may result in decreased plasma concentrations of dronabinol. Dronabinol is a CYP2C9 and 3A4 substrate; rifabutin is a moderate inducer of CYP3A4.
Drospirenone; Estradiol: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Drospirenone; Ethinyl Estradiol: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Drospirenone; Ethinyl Estradiol; Levomefolate: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Duvelisib: (Major) Avoid concomitant use of duvelisib with rifabutin. Coadministration may decrease the exposure of duvelisib, which may reduce the efficacy of duvelisib; rifabutin exposure may also be increased. If concomitant use is necessary, increase the dose of duvelisib on day 12 of coadministration from 25 mg PO twice daily to 40 mg PO twice daily; or from 15 mg PO twice daily to 25 mg PO twice daily. Monitor for rifabutin-related adverse reactions. When rifabutin has been discontinued for at least 14 days, resume duvelisib at the dose taken prior to initiating treatment with rifabutin. Duvelisib is a CYP3A substrate and a moderate CYP3A4 inhibitor. Rifabutin is a CYP3A4 substrate and a moderate CYP3A inducer. Coadministration of duvelisib with another moderate CYP3A inducer for 12 days decreased duvelisib exposure by 35%.
Efavirenz: (Major) Due to decreased exposure of rifabutin, the FDA-approved labeling recommends that the daily dose of rifabutin be increased by 50% when coadministered with efavirenz. For patients being treated for tuberculosis, guidelines recommend a daily dose of 450 to 600 mg. For rifabutin regimens given two or three times per week, consider doubling the rifabutin dose. Rifabutin is a substrate of CYP3A4; efavirenz is a moderate CYP3A4 inducer.
Efavirenz; Emtricitabine; Tenofovir Disoproxil Fumarate: (Major) Due to decreased exposure of rifabutin, the FDA-approved labeling recommends that the daily dose of rifabutin be increased by 50% when coadministered with efavirenz. For patients being treated for tuberculosis, guidelines recommend a daily dose of 450 to 600 mg. For rifabutin regimens given two or three times per week, consider doubling the rifabutin dose. Rifabutin is a substrate of CYP3A4; efavirenz is a moderate CYP3A4 inducer.
Efavirenz; Lamivudine; Tenofovir Disoproxil Fumarate: (Major) Due to decreased exposure of rifabutin, the FDA-approved labeling recommends that the daily dose of rifabutin be increased by 50% when coadministered with efavirenz. For patients being treated for tuberculosis, guidelines recommend a daily dose of 450 to 600 mg. For rifabutin regimens given two or three times per week, consider doubling the rifabutin dose. Rifabutin is a substrate of CYP3A4; efavirenz is a moderate CYP3A4 inducer.
Elacestrant: (Major) Avoid concurrent use of elacestrant and rifabutin due to the risk of decreased elacestrant exposure which may reduce its efficacy. Elacestrant is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Concomitant use with another moderate CYP3A inducer reduced elacestrant overall exposure by 55% to 73%.
Elagolix; Estradiol; Norethindrone acetate: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Elbasvir; Grazoprevir: (Major) If possible, avoid concurrent administration of elbasvir with rifabutin; consider use of an alternative hepatitis C treatment regimen. Rifabutin is a moderate CYP3A inducer, while elbasvir is a substrate of CYP3A. Use of these drugs together is expected to decrease the plasma concentrations of elbasvir, and may result in decreased virologic response. (Major) If possible, avoid concurrent administration of grazoprevir with rifabutin; consider use of an alternative hepatitis C treatment regimen. Rifabutin is a moderate CYP3A inducer, while grazoprevir is a substrate of CYP3A. Use of these drugs together is expected to decrease the plasma concentrations of grazoprevir, and may result in decreased virologic response. Conversely, concentrations of rifabutin (also a CYP3A substrate) may be increased when given with grazoprevir (a weak CYP3A inhibitor).
Elexacaftor; tezacaftor; ivacaftor: (Major) Do not administer tezacaftor; ivacaftor and rifabutin together; coadministration may reduce the efficacy of tezacaftor; ivacaftor. Exposure to ivacaftor is significantly decreased and exposure to tezacaftor may be reduced by the concomitant use of rifabutin, a strong CYP3A inducer; both tezacaftor and ivacaftor are CYP3A substrates (ivacaftor is a sensitive substrate). Coadministration of ivacaftor with a strong CYP3A inducer decreased ivacaftor exposure 89%.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Alafenamide: (Major) Avoid concurrent use of rifabutin and cobicistat-containing antiretroviral regimens. Concomitant use may decrease cobicistat exposure which may reduce its efficacy and increase rifabutin exposure and risk of adverse effects. Rifabutin is a CYP3A substrate and moderate CYP3A inducer; cobicistat is a CYP3A substrate and strong CYP3A inhibitor. (Major) Coadministration is not recommended. Concurrent use may result in significant decreases in the plasma concentrations of tenofovir alafenamide, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. (Major) Coadministration of rifabutin with elvitegravir may result in reduced elvitegravir concentrations and elevated rifabutin concentrations. If these drugs must be used concurrently, reduce the dose of rifabutin by at least 75% of the usual 300 mg/day dose (e.g., 150 mg every other day or 3x/week). If the rifabutin dose is reduced, no dose adjustment is required for elvitegravir. Monitor closely for rifabutin-associated adverse events.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Disoproxil Fumarate: (Major) Avoid concurrent use of rifabutin and cobicistat-containing antiretroviral regimens. Concomitant use may decrease cobicistat exposure which may reduce its efficacy and increase rifabutin exposure and risk of adverse effects. Rifabutin is a CYP3A substrate and moderate CYP3A inducer; cobicistat is a CYP3A substrate and strong CYP3A inhibitor. (Major) Coadministration of rifabutin with elvitegravir may result in reduced elvitegravir concentrations and elevated rifabutin concentrations. If these drugs must be used concurrently, reduce the dose of rifabutin by at least 75% of the usual 300 mg/day dose (e.g., 150 mg every other day or 3x/week). If the rifabutin dose is reduced, no dose adjustment is required for elvitegravir. Monitor closely for rifabutin-associated adverse events.
Empagliflozin; Linagliptin: (Moderate) Concomitant use of linagliptin with rifabutin may result in decreased serum concentrations of linagliptin. Linagliptin is a substrate of hepatic isoenzyme CYP3A4; rifabutin is a moderate inducer of CYP3A4. Caution and close monitoring for decreased efficacy of linagliptin are advised if these drugs are used together.
Empagliflozin; Linagliptin; Metformin: (Moderate) Concomitant use of linagliptin with rifabutin may result in decreased serum concentrations of linagliptin. Linagliptin is a substrate of hepatic isoenzyme CYP3A4; rifabutin is a moderate inducer of CYP3A4. Caution and close monitoring for decreased efficacy of linagliptin are advised if these drugs are used together.
Emtricitabine; Rilpivirine; Tenofovir alafenamide: (Major) Coadministration is not recommended. Concurrent use may result in significant decreases in the plasma concentrations of tenofovir alafenamide, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. (Major) Increase the dose of rilpivirine to 50 mg PO once daily when coadministered with rifabutin. When rifabutin coadministration is stopped, decrease the rilpivirine dose to 25 mg PO once daily. Coadministration of rilpivirine with rifabutin may result in decreased plasma concentrations of rilpivirine, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Rilpivirine is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer.
Emtricitabine; Rilpivirine; Tenofovir Disoproxil Fumarate: (Major) Increase the dose of rilpivirine to 50 mg PO once daily when coadministered with rifabutin. When rifabutin coadministration is stopped, decrease the rilpivirine dose to 25 mg PO once daily. Coadministration of rilpivirine with rifabutin may result in decreased plasma concentrations of rilpivirine, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Rilpivirine is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer.
Emtricitabine; Tenofovir alafenamide: (Major) Coadministration is not recommended. Concurrent use may result in significant decreases in the plasma concentrations of tenofovir alafenamide, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance.
Entrectinib: (Major) Avoid coadministration of entrectinib with rifabutin due to decreased entrectinib exposure and risk of decreased efficacy. Entrectinib is a CYP3A4 substrate; rifabutin is a moderate CYP3A4 inducer. Coadministration of a moderate CYP3A4 inducer is predicted to reduce the entrectinib AUC by 56%.
Erdafitinib: (Major) If coadministration of erdafitinib and rifabutin is necessary at the initiation of erdafitinib therapy, increase the dose of erdafitinib to 9 mg once daily. Erdafitinib is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Concomitant use with another moderate CYP3A inducer reduced erdafitinib overall exposure by 45%.
Erlotinib: (Major) Avoid the coadministration of erlotinib with rifabutin if possible due to the risk of decreased erlotinib efficacy. If concomitant use is unavoidable, increase the dose of erlotinib by 50 mg increments at 2-week intervals as tolerated, to a maximum of 450 mg. Erlotinib is a CYP3A4 substrate and rifabutin is a CYP3A4 inducer. Coadministration may decrease plasma concentrations of erlotinib.
Erythromycin: (Moderate) Caution is warranted when erythromycin is administered with rifabutin as rifabutin concentrations may be elevated. Monitor for adverse events of rifabutin, such as neutropenia and rash. Erythromycin is an inhibitor of CYP3A4, and rifabutin is a substrate of CYP3A4.
Escitalopram: (Moderate) CYP3A4 and CYP2C19 are the primary isozymes involved in the N-demethylation of escitalopram. Rifabutin can induce the metabolism of escitalopram via induction of CYP3A4. Given the enzyme-inducing properties rifabutin, the possibility that the drug may increase the clearance of escitalopram should be considered if the 2 drugs are coadministered.
Esterified Estrogens: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Esterified Estrogens; Methyltestosterone: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Estradiol: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Estradiol; Levonorgestrel: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Estradiol; Norethindrone: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Estradiol; Norgestimate: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Estradiol; Progesterone: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Estrogens affected by CYP3A inducers: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Estropipate: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Ethambutol: (Moderate) Careful monitoring of hepatic function is recommended with the concurrent use of rifabutin and ethambutol. Each drug has the potential to cause hepatotoxicity, and hepatotoxicity risk may be increased with concomitant use. These drugs are often used together for the treatment of active tuberculosis (TB) infection, and patients should also be assessed for additional risk factors for hepatotoxicity, such as other hepatotoxic drugs, alcohol use, and underlying hepatic disease. Any adverse event leading to hospitalization or death should be reported to local or state health departments as well as the FDA MedWatch program.
Ethinyl Estradiol; Norelgestromin: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Ethinyl Estradiol; Norethindrone Acetate: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Ethinyl Estradiol; Norgestrel: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Ethionamide: (Moderate) Careful monitoring of hepatic function is recommended with the concurrent use of rifabutin and ethionamide. Each drug has the potential to cause hepatotoxicity, and hepatotoxicity risk may be increased with concomitant use. These drugs may be used together for the treatment of active tuberculosis (TB) infection, and patients should also be assessed for additional risk factors for hepatotoxicity, such as other hepatotoxic drugs, alcohol use, and underlying hepatic disease. Any adverse event leading to hospitalization or death should be reported to local or state health departments as well as the FDA MedWatch program.
Ethotoin: (Moderate) Drugs that induce hepatic microsomal enzymes, particularly those drugs that increase CYP2C9 or CYP2C19 metabolism, such as rifamycins, can accelerate hydantoin anticonvulsant clearance.
Ethynodiol Diacetate; Ethinyl Estradiol: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Etonogestrel; Ethinyl Estradiol: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Etravirine: (Moderate) If a patient's antiretroviral treatment regimen contains etravirine and a protease inhibitor boosted with ritonavir (i.e., either darunavir or saquinavir with ritonavir), then rifabutin should not be coadministered due to the potential for significant reductions in etravirine exposure. However, if the antiretroviral regimen does not contain a protease inhibitor boosted with ritonavir, then rifabutin may be used (at a dose of 300 mg daily).
Everolimus: (Moderate) Monitor everolimus whole blood trough concentrations as appropriate if coadministration with rifabutin is necessary. The dose of everolimus may need to be increased. Everolimus is a sensitive CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Coadministration with CYP3A4 inducers may increase the metabolism of everolimus and decrease everolimus blood concentrations.
Ezetimibe; Simvastatin: (Minor) Rifabutin may induce the CYP3A4 metabolism of simvastatin. Monitor for potential reduced cholesterol-lowering and hypotensive efficacy when these drugs are coadministered.
Fedratinib: (Major) Avoid coadministration of fedratinib with rifabutin as concurrent use may decrease fedratinib exposure which may result in decreased therapeutic response. Fedratinib is a CYP3A4 substrate; rifabutin is a moderate CYP3A4 inducer. Coadministration of fedratinib with another moderate CYP3A4 inducer decreased the overall exposure of fedratinib by 47%.
Felodipine: (Moderate) Concomitant use of felodipine and rifabutin may decrease the exposure and therapeutic efficacy of felodipine. If used together, monitor blood pressure closely; the dosage requirements of felodipine may be increased. Felodipine is a CYP3A substrate. Rifabutin is a CYP3A inducer.
Fentanyl: (Moderate) Consider an increased dose of fentanyl and monitor for evidence of opioid withdrawal if concurrent use of rifabutin is necessary. If rifabutin is discontinued, consider reducing the fentanyl dosage and monitor for evidence of respiratory depression. Coadministration of a CYP3A4 inducer like rifabutin with fentanyl, a CYP3A4 substrate, may decrease exposure to fentanyl resulting in decreased efficacy or onset of withdrawal symptoms in a patient who has developed physical dependence to fentanyl. Fentanyl plasma concentrations will increase once the inducer is stopped, which may increase or prolong the therapeutic and adverse effects, including serious respiratory depression.
Finerenone: (Major) Avoid concurrent use of finerenone and rifabutin due to the risk for decreased finerenone exposure which may reduce its efficacy. Finerenone is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Coadministration with another moderate CYP3A inducer decreased overall exposure to finerenone by 80%.
Flibanserin: (Major) Coadministration of flibanserin with rifabutin is not recommended due to decreased plasma concentrations of flibanserin. Flibanserin is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Coadministration with another moderate CYP3A4 inducer decreased flibanserin exposure by approximately 21%.
Fluconazole: (Moderate) Monitor for rifabutin-associated adverse effects with concomitant fluconazole use. Reduce the rifabutin dose or discontinue rifabutin if toxicity is suspected. Carefully monitor for uveitis when rifabutin is given concomitantly with fluconazole. If uveitis is suspected, refer the patient to an ophthalmologist, and if considered necessary, discontinue rifabutin. Coadministration of fluconazole increased the rifabutin AUC by 82% and Cmax by 88%.
Fluphenazine: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin.
Flurazepam: (Moderate) Several hepatic inducers, including rifabutin, can theoretically increase the clearance of benzodiazepines metabolized by oxidative metabolism, leading to lower benzodiazepine concentrations.
Fluvastatin: (Minor) Rifampin has been reported to significantly increase the plasma clearance and decrease the serum concentrations of fluvastatin, with the potential for reduced antilipemic efficacy. Although not studied, a similar interaction can be expected between other rifamycins (e.g., rifabutin, rifapentine) and other HMG-CoA reductase inhibitors. To evaluate this interaction, monitor serum lipid concentrations during coadministration of rifamycins with HMG-CoA reductase inhibitors.
Fosamprenavir: (Major) Reduce rifabutin dose to 150 mg PO once daily and monitor for adverse effects, such as uveitis and neutropenia, if concomitant use of fosamprenavir is necessary. Concomitant use may increase rifabutin exposure. There are no clinically significantly alterations in fosamprenavir pharmacokinetics. Rifabutin is a CYP3A substrate and fosamprenavir is a moderate CYP3A inhibitor. Coadministration with fosamprenavir/ritonavir significantly increased the AUC of the active metabolite of rifabutin.
Fosphenytoin: (Moderate) Drugs that induce hepatic microsomal enzymes, particularly those drugs that increase CYP2C9 or CYP2C19 metabolism, such as rifamycins, can accelerate hydantoin anticonvulsant clearance.
Fruquintinib: (Major) Avoid coadministration of fruquintinib with rifabutin if possible due to decreased fruquintinib exposure and risk of decreased efficacy. If concomitant use of fruquintinib and rifabutin is necessary, monitor for decreased efficacy. Fruquintinib is a CYP3A substrate; rifabutin is a strong CYP3A inducer. Coadministration of a moderate CYP3A inducer is predicted to decrease fruquintinib exposure by 32%.
Ganaxolone: (Major) Avoid concurrent use of ganaxolone and rifabutin due to the risk of decreased ganaxolone efficacy. If concomitant use is unavoidable, consider increasing ganaxolone dose without exceeding the maximum daily dose. Ganaxolone is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer.
Glasdegib: (Major) Avoid coadministration of glasdegib and rifabutin due to the potential for decreased glasdegib exposure and risk of decreased efficacy. If concurrent use cannot be avoided, increase the glasdegib dosage (i.e., from 100 mg PO daily to 200 mg PO daily; or from 50 mg PO daily to 100 mg PO daily). Resume the previous dose of glasdegib after rifabutin has been discontinued for 7 days. Glasdegib is a CYP3A4 substrate; rifabutin is a moderate CYP3A4 inducer. Coadministration with another moderate CYP3A4 inducer was predicted to decrease the glasdegib AUC value by 55%.
Glecaprevir; Pibrentasvir: (Major) When possible, avoid concurrent administration of glecaprevir and rifabutin; consider use of an alternative hepatitis C treatment. Use of these drugs together may decrease the plasma concentration of glecaprevir. Use of another rifamycin with glecaprevir resulted in an 88% decrease in the plasma concentration of glecaprevir. (Major) When possible, avoid concurrent administration of pibrentasvir and rifabutin; consider use of an alternative hepatitis C treatment. Use of these drugs together may decrease the plasma concentration of pibrentasvir. Use of another rifamycin with pibrentasvir resulted in an 87% decrease in the plasma concentration of pibrentasvir.
Glimepiride: (Moderate) Monitor for decreased efficacy of sulfonylureas during coadministration of rifamycins as plasma concentrations of sulfonylureas may be decreased; dosage adjustments made be necessary. Sulfonylureas are CYP2C9 substrates and rifamycins are CYP2C9 inducers.
Glipizide: (Moderate) Monitor for decreased efficacy of sulfonylureas during coadministration of rifamycins as plasma concentrations of sulfonylureas may be decreased; dosage adjustments made be necessary. Sulfonylureas are CYP2C9 substrates and rifamycins are CYP2C9 inducers.
Glipizide; Metformin: (Moderate) Monitor for decreased efficacy of sulfonylureas during coadministration of rifamycins as plasma concentrations of sulfonylureas may be decreased; dosage adjustments made be necessary. Sulfonylureas are CYP2C9 substrates and rifamycins are CYP2C9 inducers.
Glyburide: (Moderate) Monitor for decreased efficacy of sulfonylureas during coadministration of rifamycins as plasma concentrations of sulfonylureas may be decreased; dosage adjustments made be necessary. Sulfonylureas are CYP2C9 substrates and rifamycins are CYP2C9 inducers.
Glyburide; Metformin: (Moderate) Monitor for decreased efficacy of sulfonylureas during coadministration of rifamycins as plasma concentrations of sulfonylureas may be decreased; dosage adjustments made be necessary. Sulfonylureas are CYP2C9 substrates and rifamycins are CYP2C9 inducers.
Guanfacine: (Major) Rifabutin may significantly decrease guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if these agents are taken together, doubling the recommended dose of guanfacine should be considered; if rifabutin is added in a patient already receiving guanfacine, this escalation should occur over 1 to 2 weeks. If rifabutin is discontinued, decrease the guanfacine ER dosage back to the recommended dose over 1 to 2 weeks. Specific recommendations for immediate-release (IR) guanfacine are not available. Guanfacine is primarily metabolized by CYP3A4, and rifabutin is a moderate CYP3A4 inducer.
Haloperidol: (Major) Significant reductions in haloperidol plasma concentrations have been reported during concurrent use of haloperidol and CYP3A4 enzyme-inducing drugs such as carbamazepine or rifampin. Rifabutin is an inducer and a substrate of CYP3A4. Haloperidol dosage adjustments should be made as needed when rifabutin is added or discontinued.
Homatropine; Hydrocodone: (Moderate) Monitor for reduced efficacy of hydrocodone and signs of opioid withdrawal in patients who have developed physical dependence if coadministration with rifabutin is necessary; consider increasing the dose of hydrocodone as needed. It is recommended to avoid this combination when hydrocodone is being used for cough. If rifabutin is discontinued, consider a dose reduction of hydrocodone and frequently monitor for signs of respiratory depression and sedation. Hydrocodone is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Concomitant use can decrease hydrocodone levels.
Hydantoins: (Moderate) Drugs that induce hepatic microsomal enzymes, particularly those drugs that increase CYP2C9 or CYP2C19 metabolism, such as rifamycins, can accelerate hydantoin anticonvulsant clearance.
Hydrocodone: (Moderate) Monitor for reduced efficacy of hydrocodone and signs of opioid withdrawal in patients who have developed physical dependence if coadministration with rifabutin is necessary; consider increasing the dose of hydrocodone as needed. It is recommended to avoid this combination when hydrocodone is being used for cough. If rifabutin is discontinued, consider a dose reduction of hydrocodone and frequently monitor for signs of respiratory depression and sedation. Hydrocodone is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Concomitant use can decrease hydrocodone levels.
Hydrocodone; Ibuprofen: (Moderate) Monitor for reduced efficacy of hydrocodone and signs of opioid withdrawal in patients who have developed physical dependence if coadministration with rifabutin is necessary; consider increasing the dose of hydrocodone as needed. It is recommended to avoid this combination when hydrocodone is being used for cough. If rifabutin is discontinued, consider a dose reduction of hydrocodone and frequently monitor for signs of respiratory depression and sedation. Hydrocodone is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Concomitant use can decrease hydrocodone levels.
Ibrexafungerp: (Major) Avoid concurrent administration of ibrexafungerp with rifabutin. Use of these drugs together is expected to significantly decrease ibrexafungerp exposure, which may reduce its efficacy. Ibrexafungerp is a CYP3A substrate and rifabutin is a moderate CYP3A inducer.
Ibrutinib: (Moderate) Use ibrutinib and rifabutin together with caution; decreased ibrutinib levels may occur resulting in reduced ibrutinib efficacy. Monitor patients for signs of decreased ibrutinib efficacy if these agents are used together. Ibrutinib is a CYP3A4 substrate; rifabutin is a moderate CYP3A inducer. Simulations suggest that coadministration with a moderate CYP3A4 inducer may decrease ibrutinib exposure by 3-fold.
Ibuprofen; Oxycodone: (Moderate) Monitor for reduced efficacy of oxycodone and signs of opioid withdrawal if coadministration with rifabutin is necessary; consider increasing the dose of oxycodone as needed. If rifabutin is discontinued, consider a dose reduction of oxycodone and frequently monitor for signs of respiratory depression and sedation. Oxycodone is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease oxycodone concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Idelalisib: (Contraindicated) Avoid concomitant use of idelalisib, a strong CYP3A inhibitor, with rifabutin, a CYP3A substrate, as rifabutin toxicities may be significantly increased. The AUC of a sensitive CYP3A substrate was increased 5.4-fold when coadministered with idelalisib.
Ifosfamide: (Moderate) Closely monitor for increased ifosfamide-related toxicities (e.g., neurotoxicity, nephrotoxicity) if coadministration with rifabutin is necessary; consider adjusting the dose of ifosfamide as clinically appropriate. Ifosfamide is metabolized to its active alkylating metabolites by CYP3A4; rifabutin is a moderate CYP3A4 inducer. Concomitant use may increase the formation of the neurotoxic/nephrotoxic ifosfamide metabolite, chloroacetaldehyde.
Indinavir: (Major) Reduce rifabutin dose to 150 mg PO once daily and increase indinavir dose from 800 mg to 1,000 mg 3 times daily if concomitant use is necessary. Monitor for decrease in indinavir efficacy and for rifabutin-related adverse effects, such as uveitis and neutropenia. Concomitant use may increase rifabutin exposure and decrease indinavir exposure. Rifabutin is a CYP3A substrate and moderate CYP3A inducer; indinavir is a CYP3A substrate and strong CYP3A inhibitor. Coadministration increased rifabutin exposure by 173% and decreased indinavir exposure by 34%.
Infigratinib: (Major) Avoid concurrent use of infigratinib and rifabutin. Coadministration may decrease infigratinib exposure resulting in decreased efficacy. Infigratinib is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer.
Isavuconazonium: (Major) Caution and close monitoring are warranted when isavuconazonium is administered with rifabutin as there is a potential for elevated rifabutin concentrations and decreased concentrations of isavuconazonium. Decreased isavuconazonium concentrations may lead to a reduction of antifungal efficacy and the potential for treatment failure. Rifabutin is a substrate and inducer of the hepatic isoenzyme CYP3A4. Isavuconazole, the active moiety of isavuconazonium, is a sensitive substrate and moderate inhibitor of this enzyme.
Isoniazid, INH: (Moderate) Careful monitoring of hepatic function is recommended with the concurrent use of rifabutin and isoniazid, INH. Each drug has the potential to cause hepatotoxicity, and hepatotoxicity risk may be increased with concomitant use. These drugs are often used together for the treatment of active tuberculosis (TB) infection, and patients should also be assessed for additional risk factors for hepatotoxicity, such as other hepatotoxic drugs, alcohol use, and underlying hepatic disease. Any adverse event leading to hospitalization or death should be reported to local or state health departments as well as the FDA MedWatch program.
Isoniazid, INH; Pyrazinamide, PZA; Rifampin: (Moderate) Careful monitoring of hepatic function is recommended with the concurrent use of rifabutin and isoniazid, INH. Each drug has the potential to cause hepatotoxicity, and hepatotoxicity risk may be increased with concomitant use. These drugs are often used together for the treatment of active tuberculosis (TB) infection, and patients should also be assessed for additional risk factors for hepatotoxicity, such as other hepatotoxic drugs, alcohol use, and underlying hepatic disease. Any adverse event leading to hospitalization or death should be reported to local or state health departments as well as the FDA MedWatch program. (Moderate) Careful monitoring of hepatic function is recommended with the concurrent use of rifabutin and pyrazinamide, PZA. Each drug has the potential to cause hepatotoxicity, and hepatotoxicity risk may be increased with concomitant use. These drugs are often used together for the treatment of active tuberculosis (TB) infection, and patients should also be assessed for additional risk factors for hepatotoxicity, such as other hepatotoxic drugs, alcohol use, and underlying hepatic disease. Any adverse event leading to hospitalization or death should be reported to local or state health departments as well as the FDA MedWatch program.
Isoniazid, INH; Rifampin: (Moderate) Careful monitoring of hepatic function is recommended with the concurrent use of rifabutin and isoniazid, INH. Each drug has the potential to cause hepatotoxicity, and hepatotoxicity risk may be increased with concomitant use. These drugs are often used together for the treatment of active tuberculosis (TB) infection, and patients should also be assessed for additional risk factors for hepatotoxicity, such as other hepatotoxic drugs, alcohol use, and underlying hepatic disease. Any adverse event leading to hospitalization or death should be reported to local or state health departments as well as the FDA MedWatch program.
Isradipine: (Moderate) Because isradipine is a substrate of CYP3A4, the concomitant use of drugs that induce CYP3A4 such as rifabutin, may cause a reduction in the bioavailability and thus decreased therapeutic effect of isradipine. Until more data are available, patients should be monitored for potential loss of therapeutic effect when hepatic enzyme inducers are added to isradipine therapy.
Ketoconazole: (Major) Concurrent use of ketoconzole with rifabutin is not recommended. Taking these drug together may result in increased exposure to rifabutin and decreased exposure to ketoconazole. Both drugs are substrates for CYP3A4, while rifabutin is also a CYP3A4 inducer and ketoconazole is a potent inhibitor of CYP3A4.
Lamivudine, 3TC; Zidovudine, ZDV: (Minor) Rifabutin may accelerate the metabolism of zidovudine. However the effectiveness of zidovudine against HIV does not appear to be altered and no dosage adjustments are required. The CDC currently considers the nucleoside reverse transcriptase inhibitors, including zidovudine, compatible for concomitant use with rifamycins, including rifampin, rifabutin and rifapentine.
Lansoprazole; Amoxicillin; Clarithromycin: (Major) The combination of rifabutin and clarithromycin should be avoided. Clarithromycin is a substrate and inhibitor of CYP3A4, and rifabutin is a substrate and inducer of CYP3A4. The metabolism of rifabutin is inhibited by clarithromycin, possibly through inhibition of CYP3A4. Inhibition of rifabutin metabolism results in significant increases in rifabutin serum concentrations and adverse reactions. Also, rifabutin increases the metabolism of clarithromycin resulting in significant decreases in clarithromycin concentrations thereby reducing the antimicrobial efficacy of clarithromycin. As compared with the plasma concentration obtained with clarithromycin monotherapy, the clarithromycin plasma concentration was reduced by 63% when rifabutin 600 mg daily was coadministered. Specifically, as monotherapy, the mean serum clarithromycin concentration was 5.4 +/- 2.1 mcg/ml. The mean serum clarithromycin concentration was 2 +/- 1.5 mcg/ml when given in combination with rifabutin. The mean serum concentrations of 14-OH clarithromycin were similar between the two groups.
Larotrectinib: (Major) Avoid concurrent use of larotrectinib and rifabutin due to the risk of decreased larotrectinib exposure which may reduce its efficacy. If concomitant use is necessary, double the dose of larotrectinib and monitor response. If rifabutin is discontinued, resume the original larotrectinib dose after 3 to 5 elimination half-lives of rifabutin. Larotrectinib is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Coadministration with a moderate CYP3A inducer is predicted to decrease larotrectinib exposure by 72%.
Ledipasvir; Sofosbuvir: (Major) Avoid coadministration of ledipasvir with rifabutin. Taking these drugs together may decrease ledipasvir plasma concentrations, potentially resulting in loss of antiviral efficacy. (Major) Avoid coadministration of sofosbuvir with rifabutin. Taking these drugs together may decrease sofosbuvir plasma concentration, potentially resulting in loss of antiviral efficacy.
Lefamulin: (Major) Avoid coadministration of lefamulin with rifabutin unless the benefits outweigh the risks as concurrent use may decrease lefamulin exposure and efficacy. Lefamulin is a CYP3A4 substrate; rifabutin is a moderate CYP3A4 inducer.
Lemborexant: (Major) Avoid coadministration of lemborexant and rifabutin as concurrent use may decrease lemborexant exposure which may reduce efficacy. Lemborexant is a CYP3A4 substrate; rifabutin is a moderate CYP3A4 inducer.
Lenacapavir: (Major) Avoid concurrent use of lenacapavir and rifabutin due to the risk of decreased lenacapavir exposure which may result in loss of therapeutic effect and development of resistance. Lenacapavir is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Concomitant use with another moderate CYP3A inducer reduced lenacapavir overall exposure by 56%.
Leniolisib: (Major) Avoid concomitant use of leniolisib and rifabutin. Concomitant use may decrease leniolisib exposure which may reduce its efficacy. Leniolisib is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Concomitant use with another moderate CYP3A inducer reduced leniolisib overall exposure by 58%.
Letermovir: (Major) Concurrent administration of letermovir and rifabutin is not recommended. Use of these drugs together may decrease letermovir plasma concentrations, resulting in a potential loss of letermovir efficacy. Also, an increase in the plasma concentration of rifabutin may occur if given with letermovir. In patients who are also receiving treatment with cyclosporine, the magnitude of this interaction may be amplified. Rifabutin is a CYP3A4 substrate. Letermovir is a moderate CYP3A4 inhibitor; however, when given with cyclosporine, the combined effect on CYP3A4 substrates may be similar to a strong CYP3A4 inhibitor.
Levamlodipine: (Moderate) Rifabutin may induce the CYP3A4 metabolism of calcium-channel blockers such as amlodipine and thereby reduce their oral bioavailability. The dosage requirements of amlodipine may be increased in patients receiving concurrent enzyme inducers.
Levoketoconazole: (Major) Concurrent use of ketoconzole with rifabutin is not recommended. Taking these drug together may result in increased exposure to rifabutin and decreased exposure to ketoconazole. Both drugs are substrates for CYP3A4, while rifabutin is also a CYP3A4 inducer and ketoconazole is a potent inhibitor of CYP3A4.
Levonorgestrel; Ethinyl Estradiol: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Levonorgestrel; Ethinyl Estradiol; Ferrous Bisglycinate: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Levonorgestrel; Ethinyl Estradiol; Ferrous Fumarate: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Lidocaine: (Moderate) Concomitant use of systemic lidocaine and rifabutin may decrease lidocaine plasma concentrations. Higher lidocaine doses may be required; titrate to effect. Lidocaine is a CYP3A4 and CYP1A2 substrate; rifabutin induces CYP3A4.
Lidocaine; Epinephrine: (Moderate) Concomitant use of systemic lidocaine and rifabutin may decrease lidocaine plasma concentrations. Higher lidocaine doses may be required; titrate to effect. Lidocaine is a CYP3A4 and CYP1A2 substrate; rifabutin induces CYP3A4.
Lidocaine; Prilocaine: (Moderate) Concomitant use of systemic lidocaine and rifabutin may decrease lidocaine plasma concentrations. Higher lidocaine doses may be required; titrate to effect. Lidocaine is a CYP3A4 and CYP1A2 substrate; rifabutin induces CYP3A4.
Linagliptin: (Moderate) Concomitant use of linagliptin with rifabutin may result in decreased serum concentrations of linagliptin. Linagliptin is a substrate of hepatic isoenzyme CYP3A4; rifabutin is a moderate inducer of CYP3A4. Caution and close monitoring for decreased efficacy of linagliptin are advised if these drugs are used together.
Linagliptin; Metformin: (Moderate) Concomitant use of linagliptin with rifabutin may result in decreased serum concentrations of linagliptin. Linagliptin is a substrate of hepatic isoenzyme CYP3A4; rifabutin is a moderate inducer of CYP3A4. Caution and close monitoring for decreased efficacy of linagliptin are advised if these drugs are used together.
Lonafarnib: (Contraindicated) Coadministration of lonafarnib and rifabutin is contraindicated; concurrent use may decrease lonafarnib exposure, which may reduce its efficacy. Rifabutin exposure and the risk for rifabutin-related adverse effects may also be increased; rifabutin dosage adjustments may be required if concomitant use is necessary. Lonafarnib is a sensitive CYP3A4 substrate and strong CYP3A4 inhibitor and rifabutin is a CYP3A4 substrate and moderate CYP3A4 inducer.
Lopinavir; Ritonavir: (Major) Reduce the rifabutin dose to 150 mg PO once daily and monitor for adverse effects, such as uveitis and neutropenia, if concomitant use with lopinavir; ritonavir is necessary. Although the FDA-approved labeling recommends reducing the rifabutin dose by at least 75% (to a maximum 150 mg every other day or 3 times per week), lower rifabutin exposure has been reported in persons living with HIV than in healthy subjects and acquired rifamycin resistance has been reported in these persons receiving 3 times weekly regimens. Monitor response and consider therapeutic drug monitoring (TDM) when rifabutin is used with lopinavir; ritonavir and adjust dose accordingly. Rifabutin is a CYP3A substrate and lopinavir; ritonavir is a strong CYP3A inhibitor. Coadministration with lopinavir; ritonavir increased the AUC of rifabutin by approximately 200%. (Major) Reduce the rifabutin dose to 150 mg PO once daily and monitor for adverse effects, such as uveitis and neutropenia, if concomitant use with ritonavir is necessary. Although the FDA-approved labeling recommends reducing the rifabutin dose by at least 75% (to a maximum 150 mg every other day or 3 times per week), lower rifabutin exposure has been reported in persons living with HIV than in healthy subjects and acquired rifamycin resistance has been reported in these persons receiving 3 times weekly regimens. Monitor response and consider therapeutic drug monitoring (TDM) when rifabutin is used with a ritonavir-boosted protease inhibitor and adjust dose accordingly. Rifabutin is a CYP3A substrate and ritonavir is a strong CYP3A inhibitor. Coadministration with ritonavir (alone) increased the AUC of rifabutin by 300%.
Lorlatinib: (Major) Avoid concomitant use of lorlatinib and rifabutin due to decreased plasma concentrations of lorlatinib, which may reduce its efficacy. If concomitant use is necessary, increase the dose of lorlatinib to 125 mg PO once daily. Lorlatinib is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Administration with another moderate CYP3A inducer decreased lorlatinib exposure by 23%.
Lovastatin: (Minor) Rifampin has been reported to significantly increase the plasma clearance and decrease the serum concentrations of atorvastatin, simvastatin and fluvastatin, with the potential for reduced antilipemic efficacy. Although not studied, a similar interaction can be expected between other rifamycins (e.g., rifabutin, rifapentine) and other HMG-CoA reductase inhibitors (Statins). To evaluate this interaction, monitor serum lipid concentrations during coadministration of rifamycins with HMG-CoA reductase inhibitors.
Lumacaftor; Ivacaftor: (Major) Concomitant use of rifabutin and lumacaftor; ivacaftor is not recommended. Rifabutin may decrease the therapeutic effect of lumacaftor; ivacaftor by significantly decreasing the systemic exposure of ivacaftor. Lumacaftor; ivacaftor may also decrease the therapeutic effect of rifabutin. Rifabutin is a substrate and potent inducer (per FDA-approved labeling for lumacaftor; ivacaftor) of CYP3A. Ivacaftor is a substrate of CYP3A and lumacaftor is a potent inducer of CYP3A; although the enzyme induction effects of lumacaftor are already accounted for in fixed-combination dosing, ivacaftor exposure is further decreased when given together with other CYP3A inducers. In a pharmacokinetic study, coadministration of lumacaftor; ivacaftor with rifampin, another potent CYP3A inducer, decreased ivacaftor exposure (AUC) by 57%, with minimal effect on the exposure of lumacaftor. Rifabutin may be expected to have a similar effect on some drugs that are affected by coadministration with rifampin. Rifabutin appears to be a less potent hepatic enzyme inducer than rifampin; however, the clinical significance of this finding has not been determined.
Lumacaftor; Ivacaftor: (Major) Concomitant use of rifabutin and lumacaftor; ivacaftor is not recommended. Rifabutin may decrease the therapeutic effect of lumacaftor; ivacaftor by significantly decreasing the systemic exposure of ivacaftor. Lumacaftor; ivacaftor may also decrease the therapeutic effect of rifabutin. Rifabutin is a substrate and potent inducer (per FDA-approved labeling for lumacaftor; ivacaftor) of CYP3A. Ivacaftor is a substrate of CYP3A and lumacaftor is a potent inducer of CYP3A; although the enzyme induction effects of lumacaftor are already accounted for in fixed-combination dosing, ivacaftor exposure is further decreased when given together with other CYP3A inducers. In a pharmacokinetic study, coadministration of lumacaftor; ivacaftor with rifampin, another potent CYP3A inducer, decreased ivacaftor exposure (AUC) by 57%, with minimal effect on the exposure of lumacaftor. Rifabutin may be expected to have a similar effect on some drugs that are affected by coadministration with rifampin. Rifabutin appears to be a less potent hepatic enzyme inducer than rifampin; however, the clinical significance of this finding has not been determined.
Lumateperone: (Major) Avoid coadministration of lumateperone and rifabutin as concurrent use may decrease lumateperone exposure which may reduce efficacy. Lumateperone is a CYP3A4 substrate; rifabutin is a moderate CYP3A4 inducer.
Lurasidone: (Moderate) Because lurasidone is primarily metabolized by CYP3A4, decreased plasma concentrations of lurasidone may occur when the drug is co-administered with inducers of CYP3A4. Concurrent use of lurasidone and CYP3A4 inducers, such as rifabutin, may lead to a decrease in efficacy of lurasidone. If lurasidone is used with a moderate CYP3A4 inducer, it may be necessary to increase the lurasidone dose after chronic treatment (7 days or more).
Maraviroc: (Moderate) Use caution if coadministration of maraviroc with rifabutin is necessary, due to a possible decrease in maraviroc exposure. Maraviroc is a CYP3A substrate and rifabutin is a CYP3A4 inducer. Monitor for a decrease in maraviroc efficacy with concomitant use.
Maribavir: (Major) Avoid concomitant use of maribavir and rifabutin. Coadministration may decrease maribavir exposure resulting in reduced virologic response. Maribavir is a CYP3A substrate and rifabutin is a moderate CYP3A inducer.
Mavacamten: (Contraindicated) Mavacamten is contraindicated for use with rifabutin due to risk for reduced mavacamten efficacy. Concomitant use decreases mavacamten exposure. Mavacamten is a CYP3A substrate and rifabutin is a moderate CYP3A inducer.
Mebendazole: (Moderate) Mebendazole is metabolized by hepatic cytochrome P450 enzymes and other enzymes. Rifamycins induce hepatic microsomal enzymes and may increase the metabolism of mebendazole if given concomitantly.
Mefloquine: (Moderate) Mefloquine is metabolized by CYP3A4. Rifabutin is an inducer of CYP3A4, and may increase the metabolism of mefloquine and reduce mefloquine plasma concentrations if coadministered.
Metformin; Repaglinide: (Minor) Repaglinide is metabolized in the liver by cytochrome P450 isoenzyme CYP3A4. Patients taking repaglinide concomitantly with a CYP3A4 inducer, such as rifabutin, should be monitored for reduced effectiveness of repaglinide and possible symptoms indicating hyperglycemia.
Midazolam: (Moderate) Rifabutin is an inducer of the hepatic isoenzyme CYP3A4, one of the pathways responsible for the hepatic metabolism of midazolam. Patients receiving rifabutin may require higher doses of midazolam to achieve the desired clinical effect.
Mitapivat: (Major) Avoid coadministration of mitapivat with rifabutin, if possible, due to decreased mitapivat efficacy. Coadministration decreases mitapivat concentrations. If concomitant use is necessary, up-titration of mitapivat may be required. Monitor hemoglobin and titrate the mitapivat dose based on response; do not exceed 100 mg PO twice daily. Mitapivat is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Coadministration with another moderate CYP3A inducer decreased mitapivat overall exposure by 55% to 60%.
Mitotane: (Major) Use caution if mitotane and rifabutin are used concomitantly, and monitor for decreased efficacy of rifabutin and a possible change in dosage requirements. Mitotane is a strong CYP3A4 inducer and rifabutin is a CYP3A4 substrate; coadministration may result in decreased plasma concentrations of rifabutin.
Mobocertinib: (Major) Avoid concomitant use of mobocertinib and rifabutin. Coadministration may decrease mobocertinib exposure resulting in decreased efficacy. Mobocertinib is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Use of a moderate CYP3A inducer is predicted to decrease the overall exposure of mobocertinib and its active metabolites by 58%.
Modafinil: (Moderate) Drugs that exhibit significant induction of the hepatic microsomal CYP3A4 isoenzyme may potentially increase the metabolism of modafinil. These medications include rifabutin. Decreased serum levels of modafinil could potentially result in decreased efficacy of modafinil.
Nanoparticle Albumin-Bound Paclitaxel: (Moderate) Monitor for decreased efficacy of nab-paclitaxel if coadministration with rifabutin is necessary due to the risk of decreased plasma concentrations of paclitaxel. Nab-paclitaxel is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer.
Nanoparticle Albumin-Bound Sirolimus: (Moderate) Monitor for reduced sirolimus efficacy if sirolimus is coadministered with rifabutin. Concomitant use may decrease sirolimus exposure. Sirolimus is a CYP3A substrate and rifabutin is a moderate CYP3A inducer.
Nelfinavir: (Major) Reduce rifabutin dose to 150 mg PO once daily and increase nelfinavir dose to 1,250 mg PO every 12 hours if concomitant use is necessary. Rifabutin is a CYP3A substrate and moderate CYP3A inducer; nelfinavir is a CYP3A substrate and strong CYP3A inhibitor. While coadministration of nelfinavir 750 mg every 8 hours with rifabutin 300 mg once daily resulted in a 32% decrease in nelfinavir exposure and a 207% increase in rifabutin exposure, the coadministration of nelfinavir 1,250 mg every 12 hours with rifabutin 150 mg once daily resulted in no alterations in nelfinavir exposure.
Neratinib: (Major) Avoid concomitant use of rifabutin with neratinib due to decreased efficacy of neratinib. Neratinib is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Simulations using physiologically based pharmacokinetic (PBPK) models suggest that another moderate CYP3A4 inducer may decrease neratinib exposure by 52%.
Nicardipine: (Moderate) Rifabutin may induce the CYP3A4 metabolism of calcium-channel blockers such as nicardipine and thereby reduce their oral bioavailability. The dosage requirements of nicardipine may be increased in patients receiving concurrent enzyme inducers.
NIFEdipine: (Major) Avoid coadministration of nifedipine with rifabutin and consider alternative therapy if possible. If coadministration is necessary, monitor the patient closely for desired cardiovascular effects on heart rate, blood pressure, or chest pain. Nifedipine is a CYP3A substrate and rifabutin is a CYP3A inducer.
Nimodipine: (Moderate) Rifabutin may induce the CYP3A4 metabolism of calcium-channel blockers such as nimodipine and thereby reduce their oral bioavailability. The dosage requirements of nimodipine may be increased in patients receiving concurrent enzyme inducers.
Niraparib; Abiraterone: (Moderate) Concomitant use of abiraterone with rifabutin may result in decreased serum concentrations of abiraterone. Abiraterone is a substrate of hepatic isoenzyme CYP3A4; rifabutin is a moderate inducer of this enzyme. Caution and close monitoring for decreased efficacy are advised if these drugs are used together.
Nirmatrelvir; Ritonavir: (Major) Reduce the rifabutin dose to 150 mg PO once daily and monitor for adverse effects, such as uveitis and neutropenia, if concomitant use with ritonavir is necessary. Although the FDA-approved labeling recommends reducing the rifabutin dose by at least 75% (to a maximum 150 mg every other day or 3 times per week), lower rifabutin exposure has been reported in persons living with HIV than in healthy subjects and acquired rifamycin resistance has been reported in these persons receiving 3 times weekly regimens. Monitor response and consider therapeutic drug monitoring (TDM) when rifabutin is used with a ritonavir-boosted protease inhibitor and adjust dose accordingly. Rifabutin is a CYP3A substrate and ritonavir is a strong CYP3A inhibitor. Coadministration with ritonavir (alone) increased the AUC of rifabutin by 300%. (Moderate) Monitor for a diminished response to nirmatrelvir if concomitant use of rifabutin is necessary. Concomitant use of nirmatrelvir and rifabutin may reduce the therapeutic effect of nirmatrelvir. Nirmatrelvir is a CYP3A substrate and rifabutin is a moderate CYP3A inducer.
Nirogacestat: (Major) Avoid concomitant use of nirogacestat and rifabutin. Concurrent use may decrease nirogacestat exposure which may reduce its efficacy. Nirogacestat is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Concomitant use with another moderate CYP3A inducer is predicted to reduce nirogacestat overall exposure by 67%.
Nisoldipine: (Major) Avoid coadministration of nisoldipine with rifabutin due to decreased plasma concentrations of nisoldipine. Alternative antihypertensive therapy should be considered. Nisoldipine is a CYP3A4 substrate and rifabutin is a CYP3A4 inducer. Coadministration with a strong CYP3A4 inducer lowered nisoldipine plasma concentrations to undetectable levels.
Norethindrone Acetate; Ethinyl Estradiol; Ferrous fumarate: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Norethindrone; Ethinyl Estradiol: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Norethindrone; Ethinyl Estradiol; Ferrous fumarate: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Norgestimate; Ethinyl Estradiol: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Olaparib: (Major) Avoid coadministration of olaparib with rifabutin due to the risk of decreasing the efficacy of olaparib. Olaparib is a CYP3A substrate and rifabutin is a moderate CYP3A4 inducer; concomitant use may decrease olaparib exposure. Coadministration with a moderate CYP3A inducer is predicted to decrease the olaparib Cmax by 31% and the AUC by 60%.
Olmesartan; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Rifabutin may induce the CYP3A4 metabolism of calcium-channel blockers such as amlodipine and thereby reduce their oral bioavailability. The dosage requirements of amlodipine may be increased in patients receiving concurrent enzyme inducers.
Olutasidenib: (Major) Avoid concurrent use of olutasidenib and rifabutin due to the risk of decreased olutasidenib exposure which may reduce its efficacy. Olutasidenib is a CYP3A substrate and rifabutin is a moderate CYP3A inducer.
Omaveloxolone: (Major) Avoid concurrent use of omaveloxolone and rifabutin. Concurrent use may decrease omaveloxolone exposure which may reduce its efficacy. Omaveloxone is a CYP3A substrate and rifabutin is a moderate CYP3A inducer.
Ondansetron: (Minor) Monitor for altered response to ondansetron during coadministration of rifabutin. Rifabutin may increase the clearance and decrease blood concentrations of ondansetron. However, no dosage adjustment for ondansetron is recommended during coadministration.
Oritavancin: (Moderate) Rifabutin is metabolized by CYP3A4; oritavancin is a weak CYP3A4 inducer. Plasma concentrations and efficacy of rifabutin may be reduced if these drugs are administered concurrently.
Oxycodone: (Moderate) Monitor for reduced efficacy of oxycodone and signs of opioid withdrawal if coadministration with rifabutin is necessary; consider increasing the dose of oxycodone as needed. If rifabutin is discontinued, consider a dose reduction of oxycodone and frequently monitor for signs of respiratory depression and sedation. Oxycodone is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease oxycodone concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Paclitaxel: (Minor) Paclitaxel is metabolized by hepatic cytochrome P450 isoenzymes 2C8 and 3A4. Potential interactions may occur in vivo with any agent that induces CYP2C8 or CYP3A4 isoenzymes including rifabutin.
Pacritinib: (Major) Avoid concurrent use of pacritinib with rifabutin due to the risk of decreased pacritinib exposure which may impair efficacy. Pacritinib is a CYP3A substrate and rifabutin is a moderate CYP3A inducer.
Palovarotene: (Major) Avoid concomitant use of palovarotene and rifabutin. Concurrent use may decrease palovarotene exposure which may reduce its efficacy. Palovarotene is a CYP3A substrate and rifabutin is a moderate CYP3A inducer.
Pemigatinib: (Major) Avoid coadministration of pemigatinib and rifabutin due to the risk of decreased pemigatinib exposure which may reduce its efficacy. Pemigatinib is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Coadministration with a moderate CYP3A4 inducer is predicted to decrease pemigatinib exposure by more than 50%.
Perampanel: (Major) Start perampanel at a higher initial dose of 4 mg once daily at bedtime when using concurrently with rifabutin due to a potential reduction in perampanel plasma concentration. If introduction or withdrawal of rifabutin occurs during perampanel therapy, closely monitor patient response; a dosage adjustment may be necessary. Rifabutin is a CYP3A4 inducer, and perampanel is a CYP3A4 substrate.
Perindopril; Amlodipine: (Moderate) Rifabutin may induce the CYP3A4 metabolism of calcium-channel blockers such as amlodipine and thereby reduce their oral bioavailability. The dosage requirements of amlodipine may be increased in patients receiving concurrent enzyme inducers.
Perphenazine: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin.
Perphenazine; Amitriptyline: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin.
Phenothiazines: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin.
Phenytoin: (Moderate) Drugs that induce hepatic microsomal enzymes, particularly those drugs that increase CYP2C9 or CYP2C19 metabolism, such as rifamycins, can accelerate hydantoin anticonvulsant clearance.
Pimavanserin: (Major) Because pimavanserin is primarily metabolized by CYP3A4 and CYP3A5, the manufacturer recommends avoiding concomitant use of pimavanserin with moderate CYP3A4 inducers, such as rifabutin. Moderate inducers of CYP3A4 can reduce pimavanserin exposure, potentially decreasing the effectiveness of pimavanserin.
Pioglitazone; Glimepiride: (Moderate) Monitor for decreased efficacy of sulfonylureas during coadministration of rifamycins as plasma concentrations of sulfonylureas may be decreased; dosage adjustments made be necessary. Sulfonylureas are CYP2C9 substrates and rifamycins are CYP2C9 inducers.
Pirtobrutinib: (Major) Avoid concurrent use of pirtobrutinib and rifabutin due to the risk of decreased pirtobrutinib exposure which may reduce its efficacy. If concomitant use is necessary, an empiric pirtobrutinib dosage increase is required. If the current dosage is 200 mg once daily, increase the dose to 300 mg; if the current dosage is 50 mg or 100 mg once daily, increase the dose by 50 mg. Pirtobrutinib is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Concomitant use with other moderate CYP3A inducers reduced pirtobrutinib overall exposure by 27% and 49%.
Posaconazole: (Major) The concurrent use of posaconazole and rifabutin should be avoided, if possible, due to the potential for decreased posaconazole efficacy as well as increased risk of rifabutin related adverse events. If used in combination, closely monitor for breakthrough fungal infections and rifabutin adverse events, such as uveitis and leukopenia. Rifabutin induces UDP-glucuronidase resulting in decreased posaconazole plasma concentrations. When posaconazole (200 mg PO daily) was administered with rifabutin (300 mg PO daily), the mean reductions in Cmax were 43% and the mean reductions in AUC were 49% for posaconazole. Additionally, posaconazole is a potent inhibitor of CYP3A4, an isoenzyme responsible for the metabolism of rifabutin. Coadministration of posaconazole (200 mg PO daily) with rifabutin (300 mg PO daily) increased the mean rifabutin Cmax (by 31%) and AUC (by 72%). The concomitant use of rifabutin with posaconazole should be avoided unless the benefits outweigh the risks; dosage adjustment recommendations are not available.
Pralsetinib: (Major) Avoid concurrent use of rifabutin and pralsetinib due to the risk of decreased pralsetinib exposure which may reduce its efficacy. If concomitant use is necessary, increase the current dose of pralsetinib (400 mg to 600 mg; 300 mg to 500 mg; 200 mg to 300 mg) starting on day 7 of coadministration. Pralsetinib is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Coadministration with another moderate CYP3A inducer decreased the pralsetinib overall exposure by 45%.
Pravastatin: (Minor) Rifampin has been reported to significantly increase the plasma clearance and decrease the serum concentrations of simvastatin and fluvastatin, with the potential for reduced antilipemic efficacy. Although not studied, a similar interaction can be expected between other rifamycins (e.g., rifabutin, rifapentine) and other HMG-CoA reductase inhibitors (Statins). To evaluate this interaction, monitor serum lipid concentrations during coadministration of rifamycins with HMG-CoA reductase inhibitors.
Praziquantel: (Major) Avoid concomitant use of praziquantel and rifabutin. Concurrent use may decrease praziquantel exposure which may reduce its efficacy. If concomitant use is necessary, monitor for reduced response to praziquantel. Praziquantel is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. When praziquantel was administered after 13 days of treatment with a moderate CYP3A inducer, the mean praziquantel AUC was 77% lower than when praziquantel was given alone.
Pretomanid: (Major) Avoid coadministration of pretomanid with rifabutin as concurrent use may decrease pretomanid exposure which may lead to decreased efficacy. Pretomanid is a CYP3A4 substrate; rifabutin is a moderate CYP3A4 inducer. Coadministration with another moderate CYP3A4 inducer decreased pretomanid exposure by 35%.
Prochlorperazine: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin.
Promethazine: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin.
Promethazine; Dextromethorphan: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin.
Promethazine; Phenylephrine: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin.
Propafenone: (Moderate) Rifabutin is an inducer of the cytochrome P-450 hepatic enzyme system and can reduce the plasma concentrations and possibly the efficacy of propafenone.
Propranolol: (Moderate) Rifamycins are inducers of hepatic enzymes, and may alter the pharmacokinetics of beta-blockers including propranolol. Patients should be monitored for loss of propranolol effects if rifamycins are added.
Pyrazinamide, PZA: (Moderate) Careful monitoring of hepatic function is recommended with the concurrent use of rifabutin and pyrazinamide, PZA. Each drug has the potential to cause hepatotoxicity, and hepatotoxicity risk may be increased with concomitant use. These drugs are often used together for the treatment of active tuberculosis (TB) infection, and patients should also be assessed for additional risk factors for hepatotoxicity, such as other hepatotoxic drugs, alcohol use, and underlying hepatic disease. Any adverse event leading to hospitalization or death should be reported to local or state health departments as well as the FDA MedWatch program.
Quazepam: (Moderate) Rifabutin is a hepatic inducer and can theoretically increase the clearance of benzodiazepines metabolized by oxidative metabolism, leading to lower benzodiazepine concentrations.
Quetiapine: (Moderate) Increased doses of quetiapine may be required to maintain symptom control if rifabutin is used concomitantly. Rifabutin is a less potent inducer of CYP3A4 than rifampin, a potent inducer. However, increased doses of quetiapine up to 5 fold may be required to maintain control of symptoms in patients receiving quetiapine and known potent CYP3A4 inducers. There are no specific recommendations for moderate inducers. When rifabutin is discontinued, the dose of quetiapine should be reduced to the original level within 7 to 14 days.
Quinidine: (Moderate) Rifabutin is an inducer of the cytochrome P-450 hepatic enzyme system and can reduce the plasma concentrations and possibly the efficacy of quinidine.
Quinine: (Major) Rifabutin is an inducer of hepatic metabolism and may significantly accelerate quinine clearance and reduce its half-life. Higher doses of quinine may be required in patients receiving rifabutin.
Quizartinib: (Major) Avoid concomitant use of rifabutin with quizartinib due to the risk of decreased quizartinib exposure which may reduce its efficacy. Quizartinib is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Coadministration with another moderate CYP3A inducer decreased the quizartinib overall exposure by 90%.
Ramelteon: (Moderate) Administration of rifabutin, a CYP1A2 enzyme inducer, may theoretically result in decreased exposure to ramelteon. Monitor the patient closely if rifabutin therapy is initiated or stopped in patients receiving ramelteon.
Ranolazine: (Contraindicated) Ranolazine is contraindicated in patients receiving drugs known to be CYP3A inducers including rifabutin. Induction of CYP3A metabolism could lead to decreased ranolazine plasma concentrations and decreased efficacy.
Red Yeast Rice: (Moderate) Since certain red yeast rice products (i.e., pre-2005 Cholestin formulations) contain lovastatin, clinicians should use red yeast rice cautiously in combination with drugs known to interact with lovastatin. CYP3A4 inducers can theoretically reduce the effectiveness of HMG-CoA reductase activity via induction of CYP3A4 metabolism. Examples of CYP3A4 inducers include rifabutin.
Relugolix; Estradiol; Norethindrone acetate: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Repaglinide: (Minor) Repaglinide is metabolized in the liver by cytochrome P450 isoenzyme CYP3A4. Patients taking repaglinide concomitantly with a CYP3A4 inducer, such as rifabutin, should be monitored for reduced effectiveness of repaglinide and possible symptoms indicating hyperglycemia.
Repotrectinib: (Major) Avoid coadministration of repotrectinib with rifabutin due to decreased repotrectinib exposure and risk of decreased efficacy. Repotrectinib is a CYP3A substrate; rifabutin is a moderate CYP3A inducer.
Ribociclib: (Moderate) Monitor for an increase in rifabutin-related adverse reactions if coadministration is necessary; in some cases, the dose of rifabutin may need to be decreased. Rifabutin is a CYP3A4 substrate and ribociclib is a strong CYP3A4 inhibitor. Coadministration with CYP3A4 inhibitors may significantly increase the plasma concentration of rifabutin.
Ribociclib; Letrozole: (Moderate) Monitor for an increase in rifabutin-related adverse reactions if coadministration is necessary; in some cases, the dose of rifabutin may need to be decreased. Rifabutin is a CYP3A4 substrate and ribociclib is a strong CYP3A4 inhibitor. Coadministration with CYP3A4 inhibitors may significantly increase the plasma concentration of rifabutin.
Rilpivirine: (Major) Increase the dose of rilpivirine to 50 mg PO once daily when coadministered with rifabutin. When rifabutin coadministration is stopped, decrease the rilpivirine dose to 25 mg PO once daily. Coadministration of rilpivirine with rifabutin may result in decreased plasma concentrations of rilpivirine, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Rilpivirine is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer.
Rimegepant: (Major) Avoid coadministration of rimegepant with rifabutin; concurrent use may significantly decrease rimegepant exposure which may result in loss of efficacy. Rimegepant is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer.
Ripretinib: (Major) Avoid coadministration of ripretinib with rifabutin. If concomitant use is unavoidable, increase the frequency of ripretinib dosing from 150 mg once daily to 150 mg twice daily; monitor for clinical response and tolerability. Resume once daily dosing of ripretinib 14 days after discontinuation of rifabutin. Coadministration is predicted to decrease the exposure of ripretinib and its active metabolite (DP-5439), which may decrease ripretinib anti-tumor activity. Ripretinib and DP-5439 are metabolized by CYP3A and rifabutin is a moderate CYP3A inducer. Drug interaction modeling studies suggest coadministration with a moderate CYP3A inducer may decrease ripretinib exposure by 56%.
Ritonavir: (Major) Reduce the rifabutin dose to 150 mg PO once daily and monitor for adverse effects, such as uveitis and neutropenia, if concomitant use with ritonavir is necessary. Although the FDA-approved labeling recommends reducing the rifabutin dose by at least 75% (to a maximum 150 mg every other day or 3 times per week), lower rifabutin exposure has been reported in persons living with HIV than in healthy subjects and acquired rifamycin resistance has been reported in these persons receiving 3 times weekly regimens. Monitor response and consider therapeutic drug monitoring (TDM) when rifabutin is used with a ritonavir-boosted protease inhibitor and adjust dose accordingly. Rifabutin is a CYP3A substrate and ritonavir is a strong CYP3A inhibitor. Coadministration with ritonavir (alone) increased the AUC of rifabutin by 300%.
Rivaroxaban: (Minor) Coadministration of rivaroxaban and rifabutin may result in decreased rivaroxaban exposure and may decrease the efficacy of rivaroxaban. Rifabutin is an inducer of CYP3A4, and rivaroxaban is a substrate of CYP3A4. If these drugs are administered concurrently, monitor the patient for signs lack of efficacy of rivaroxaban.
Roflumilast: (Major) Coadminister rifabutin and roflumilast cautiously as this may lead to reduced systemic exposure to roflumilast. Rifabutin is a CYP3A4 inducer and roflumilast is a CYP3A4 substrate. In pharmacokinetic study, administration of a single dose of roflumilast in patients receiving another CYP3A4 inducer, rifampin, resulted in decreased roflumilast Cmax and AUC, as well as increased Cmax and decreased AUC of the active metabolite roflumilast N-oxide. Specific pharmacokinetic study of this potential interaction has not been conducted.
Saquinavir: (Major) Reduce the rifabutin dose to 150 mg PO once daily and monitor for adverse effects, such as uveitis and neutropenia, if concomitant use with saquinavir/ritonavir is necessary. Although the FDA-approved labeling recommends reducing the rifabutin dose by at least 75% (to a maximum 150 mg every other day or 3 times per week), lower rifabutin exposure has been reported in persons living with HIV than in healthy subjects and acquired rifamycin resistance has been reported in these persons receiving 3 times weekly regimens. Monitor response and consider therapeutic drug monitoring (TDM) when rifabutin is used with saquinavir/ritonavir and adjust dose accordingly. Rifabutin is a CYP3A substrate and saquinavir/ritonavir is a strong CYP3A inhibitor. Coadministration with saquinavir/ritonavir increased the AUC of rifabutin by approximately 50%.
Segesterone Acetate; Ethinyl Estradiol: (Major) Women taking both estrogens and rifamycins should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed rifamycins. In some cases, it may be advisable for patients to change to non-hormonal methods of birth control during rifamycin therapy. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of rifamycins. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on rifamycins, with dose adjustments made based on clinical efficacy. Estrogens are CYP3A4 substrates and rifamycins are a CYP3A4 inducers. Concurrent administration may increase estrogen elimination.
Selpercatinib: (Major) Avoid coadministration of selpercatinib and rifabutin due to the risk of decreased selpercatinib exposure which may reduce its efficacy. Selpercatinib is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Coadministration with other moderate CYP3A4 inducers is predicted to decrease selpercatinib exposure by 40% to 70%.
Selumetinib: (Major) Avoid coadministration of selumetinib and rifabutin due to the risk of decreased selumetinib exposure which may reduce its efficacy. Selumetinib is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Coadministration with a moderate CYP3A4 inducer is predicted to decrease selumetinib exposure by 38%.
Sildenafil: (Minor) Sildenafil is metabolized principally by cytochrome P450 3A4 and 2C9 enzymes. It can be expected that concomitant administration of CYP3A4 enzyme-inducers, such as rifabutin, will decrease plasma levels of sildenafil, however, no interaction studies have been performed.
Simvastatin: (Minor) Rifabutin may induce the CYP3A4 metabolism of simvastatin. Monitor for potential reduced cholesterol-lowering and hypotensive efficacy when these drugs are coadministered.
Siponimod: (Moderate) Concomitant use of siponimod and rifabutin is not recommended for patients with CYP2C9*1/*3 and *2/*3 genotypes due to a significant decrease in siponimod exposure. Siponimod is a CYP2C9 and CYP3A4 substrate; rifabutin is a moderate CYP3A4 inducer. Across different CYP2C9 genotypes, a moderate CYP3A4 inducer decreased the exposure of siponimod by up to 52% according to in silico evaluation.
Sirolimus: (Moderate) Monitor sirolimus concentrations and adjust sirolimus dosage as appropriate during concomitant use of rifabutin. Concomitant use may decrease sirolimus exposure and efficacy. Sirolimus is a CYP3A substrate and rifabutin is a moderate CYP3A inducer.
Sofosbuvir: (Major) Avoid coadministration of sofosbuvir with rifabutin. Taking these drugs together may decrease sofosbuvir plasma concentration, potentially resulting in loss of antiviral efficacy.
Sofosbuvir; Velpatasvir: (Major) Avoid coadministration of sofosbuvir with rifabutin. Taking these drugs together may decrease sofosbuvir plasma concentration, potentially resulting in loss of antiviral efficacy. (Major) Avoid coadministration of velpatasvir with inducers of CYP3A4, such as rifabutin. Taking these drugs together may significantly decrease velpatasvir plasma concentrations, potentially resulting in loss of antiviral efficacy. Velpatasvir is a CYP3A4 substrate.
Sofosbuvir; Velpatasvir; Voxilaprevir: (Major) Avoid coadministration of sofosbuvir with rifabutin. Taking these drugs together may decrease sofosbuvir plasma concentration, potentially resulting in loss of antiviral efficacy. (Major) Avoid coadministration of velpatasvir with inducers of CYP3A4, such as rifabutin. Taking these drugs together may significantly decrease velpatasvir plasma concentrations, potentially resulting in loss of antiviral efficacy. Velpatasvir is a CYP3A4 substrate. (Major) Avoid coadministration of voxilaprevir with moderate to potent inducers of CYP3A4, such as rifabutin. Taking these drugs together may significantly decrease voxilaprevir plasma concentrations, potentially resulting in loss of antiviral efficacy. Voxilaprevir is metabolized by CYP3A4.
Sonidegib: (Major) Avoid the concomitant use of sonidegib and rifabutin; sonidegib exposure may be significantly decreased and its efficacy reduced. Sonidegib is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Physiologic-based pharmacokinetics (PBPK) simulations indicate that a moderate CYP3A4 inducer would decrease the sonidegib AUC by 56% if administered for 14 days and by 69% if the moderate CYP3A inducer is administered for more than 14 days.
Sorafenib: (Major) Avoid coadministration of sorafenib with rifabutin due to decreased plasma concentrations of sorafenib. Sorafenib is a CYP3A4 substrate and rifabutin is a CYP3A4 inducer. Concomitant use with another strong CYP3A4 inducer decreased sorafenib exposure by 37%.
Sufentanil: (Moderate) Because the dose of the sufentanil sublingual tablets cannot be titrated, consider an alternate opiate if rifabutin must be administered. Monitor for reduced efficacy of sufentanil injection and signs of opioid withdrawal if coadministration with rifabutin is necessary; consider increasing the dose of sufentanil injection as needed. If rifabutin is discontinued, consider a dose reduction of sufentanil injection and frequently monitor for signs or respiratory depression and sedation. Sufentanil is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease sufentanil concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Sulfamethoxazole; Trimethoprim, SMX-TMP, Cotrimoxazole: (Moderate) Concomitant administration of rifabutin and sulfamethoxazole; trimethoprim, SMX-TMP, cotrimoxazole (double-strength) in 12 HIV-infected patients decreased the AUC of SMX-TMP by about 15 to 20%. Rifabutin decreased the AUC and Cmax of trimethoprim by 14% and 6%, respectively, when rifabutin was given with trimethoprim alone. Sulfamethoxazole; trimethoprim, SMX-TMP did not alter the pharmacokinetics of rifabutin.
Sulfonylureas: (Moderate) Monitor for decreased efficacy of sulfonylureas during coadministration of rifamycins as plasma concentrations of sulfonylureas may be decreased; dosage adjustments made be necessary. Sulfonylureas are CYP2C9 substrates and rifamycins are CYP2C9 inducers.
Tacrolimus: (Major) Increase tacrolimus dose and monitor tacrolimus serum concentrations if coadministration with rifabutin is necessary. Concurrent use may decrease tacrolimus serum concentrations and increase the risk of rejection. Tacrolimus is a sensitive CYP3A substrate with a narrow therapeutic range; rifabutin is a CYP3A inducer.
Tasimelteon: (Moderate) Caution is recommended during concurrent use of tasimelteon and rifabutin. Because tasimelteon is partially metabolized via CYP3A4, use with CYP3A4 inducers, such as rifabutin, may reduce the efficacy of tasimelteon.
Tazemetostat: (Major) Avoid coadministration of tazemetostat with rifabutin as concurrent use may decrease tazemetostat exposure, which may reduce its efficacy. Tazemetostat is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer.
Telmisartan; Amlodipine: (Moderate) Rifabutin may induce the CYP3A4 metabolism of calcium-channel blockers such as amlodipine and thereby reduce their oral bioavailability. The dosage requirements of amlodipine may be increased in patients receiving concurrent enzyme inducers.
Temsirolimus: (Major) Avoid coadministration of temsirolimus with rifabutin due to the risk of decreased plasma concentrations of the primary active metabolite of temsirolimus (sirolimus). If concomitant use is unavoidable, consider increasing the dose of temsirolimus from 25 mg per week up to 50 mg per week. If rifabutin is discontinued, decrease the dose of temsirolimus to the dose used before initiation of rifabutin. Temsirolimus is a CYP3A4 substrate and rifabutin is a CYP3A4 inducer. Coadministration with another strong CYP3A4 inducer had no significant effect on the AUC or Cmax of temsirolimus, but decreased the AUC and Cmax of the active metabolite, sirolimus, by 56% and 65%, respectively.
Tenofovir Alafenamide: (Major) Coadministration is not recommended. Concurrent use may result in significant decreases in the plasma concentrations of tenofovir alafenamide, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance.
Tenofovir Alafenamide: (Major) Coadministration is not recommended. Concurrent use may result in significant decreases in the plasma concentrations of tenofovir alafenamide, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance.
Terbinafine: (Moderate) Due to the risk for breakthrough fungal infections, caution is advised when administering terbinafine with rifabutin. Although this interaction has not been studied by the manufacturer, and published literature suggests the potential for interactions to be low, taking these drugs together may decrease the systemic exposure of terbinafine. Predictions about the interaction can be made based on the metabolic pathways of both drugs. Terbinafine is metabolized by at least 7 CYP isoenyzmes, with major contributions coming from CYP3A4; rifabutin induces this enzyme. Monitor patients for breakthrough fungal infections.
Tezacaftor; Ivacaftor: (Major) Do not administer tezacaftor; ivacaftor and rifabutin together; coadministration may reduce the efficacy of tezacaftor; ivacaftor. Exposure to ivacaftor is significantly decreased and exposure to tezacaftor may be reduced by the concomitant use of rifabutin, a strong CYP3A inducer; both tezacaftor and ivacaftor are CYP3A substrates (ivacaftor is a sensitive substrate). Coadministration of ivacaftor with a strong CYP3A inducer decreased ivacaftor exposure 89%.
Thioridazine: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin.
Thiothixene: (Major) Limited data suggest that rifampin can increase the metabolism or reduce the bioavailability of thiothixene. Dosage adjustments of thiothixene may be necessary following the addition of rifampin or another rifamycin (e.g., rifabutin, rifapentine).
Tipranavir: (Major) Reduce the rifabutin dose to 150 mg PO once daily and monitor for adverse effects, such as uveitis and neutropenia, if concomitant use with tipranavir/ritonavir is necessary. Although the FDA-approved labeling recommends reducing the rifabutin dose by at least 75% (to a maximum 150 mg every other day or 3 times per week), lower rifabutin exposure has been reported in persons living with HIV than in healthy subjects and acquired rifamycin resistance has been reported in these persons receiving 3 times weekly regimens. Monitor response and consider therapeutic drug monitoring (TDM) when rifabutin is used with tipranavir/ritonavir and adjust dose accordingly. Rifabutin is a CYP3A substrate and tipranavir/ritonavir is a strong CYP3A inhibitor. Coadministration with tipranavir/ritonavir increased the AUC of rifabutin by approximately 2.9-fold.
Toremifene: (Major) Avoid coadministration of rifabutin with toremifene due to decreased plasma concentrations of toremifene which may result in decreased efficacy. Toremifene is a CYP3A4 substrate and rifabutin is a CYP3A4 inducer. Coadministration with strong CYP3A4 inducers lowers steady-state serum concentrations of toremifene.
Tramadol; Acetaminophen: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Trandolapril; Verapamil: (Moderate) Rifabutin may induce the CYP3A4 metabolism of calcium-channel blockers such as verapamil and thereby reduce their oral bioavailability. The dosage requirements of verapamil may be increased in patients receiving concurrent enzyme inducers.
Tretinoin, ATRA: (Moderate) Rifabutin may increase the CYP450 metabolism of tretinoin, ATRA, potentially resulting in decreased plasma concentrations of tretinoin, ATRA. No specific studies have been done with oral tretinoin and rifabutin, however, patients should be closely monitored for decreased clinical effects of tretinoin, ATRA while receiving concomitant therapy.
Trifluoperazine: (Major) Rifamycins can increase the metabolism or reduce the bioavailability of phenothiazines. Dosage increases of phenothiazines may be necessary following the addition of rifampin or another rifamycin.
Trimethoprim: (Moderate) Concomitant administration of rifabutin and sulfamethoxazole; trimethoprim, SMX-TMP, cotrimoxazole (double-strength) in 12 HIV-infected patients decreased the AUC of SMX-TMP by about 15 to 20%. Rifabutin decreased the AUC and Cmax of trimethoprim by 14% and 6%, respectively, when rifabutin was given with trimethoprim alone. Sulfamethoxazole; trimethoprim, SMX-TMP did not alter the pharmacokinetics of rifabutin.
Tucatinib: (Moderate) Monitor for an increase in rifabutin-related adverse reactions if coadministration with tucatinib is necessary; in some cases, the dose of rifabutin may need to be decreased. Rifabutin is a CYP3A4 substrate and tucatinib is a strong CYP3A4 inhibitor. Coadministration with CYP3A4 inhibitors may significantly increase the plasma concentration of rifabutin.
Ubrogepant: (Major) Increase the initial and second dose of ubrogepant to 100 mg if coadministered with rifabutin as concurrent use may decrease ubrogepant exposure and reduce its efficacy. Ubrogepant is a CYP3A4 substrate; rifabutin is a moderate CYP3A4 inducer.
Ulipristal: (Major) Avoid administration of ulipristal with drugs that induce CYP3A4. Ulipristal is a substrate of CYP3A4 and rifabutin is a CYP3A4 inducer. Concomitant use is expected to decrease the plasma concentration of ulipristal and may decrease its effectiveness.
Vemurafenib: (Major) Concomitant administration of rifabutin and vemurafenib may decrease concentrations of both agents. Both rifabutin and vemurafenib are CYP3A4 substrates and inducers. Avoid using these agents together if possible.
Venetoclax: (Major) Avoid coadministration of venetoclax with rifabutin as concurrent use may decrease venetoclax exposure and lead to reduced efficacy. Venetoclax is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer.
Verapamil: (Moderate) Rifabutin may induce the CYP3A4 metabolism of calcium-channel blockers such as verapamil and thereby reduce their oral bioavailability. The dosage requirements of verapamil may be increased in patients receiving concurrent enzyme inducers.
Vincristine Liposomal: (Moderate) Vincristine is a substrate for cytochrome P450 (CYP) 3A4. Agents that induce CYP3A4 may increase the metabolism of vincristine and decrease the efficacy of the drug, including rifabutin. Patients receiving these drugs concurrently with vincristine should be monitored for possible loss of vincristine efficacy.
Vincristine: (Moderate) Vincristine is a substrate for cytochrome P450 (CYP) 3A4. Agents that induce CYP3A4 may increase the metabolism of vincristine and decrease the efficacy of the drug, including rifabutin. Patients receiving these drugs concurrently with vincristine should be monitored for possible loss of vincristine efficacy.
Voclosporin: (Major) Avoid coadministration of voclosporin with rifabutin. Coadministration may decrease voclosporin exposure resulting in decreased efficacy. Voclosporin is a sensitive CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer. Coadministration with moderate CYP3A4 inducers is predicted to decrease voclosporin exposure by 70%.
Vonoprazan: (Major) Avoid concomitant use of vonoprazan and rifabutin due to decreased plasma concentrations of vonoprazan, which may reduce its efficacy. Vonoprazan is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Vonoprazan exposures are predicted to be 50% lower when coadministered with a moderate CYP3A4 inducer.
Vonoprazan; Amoxicillin: (Major) Avoid concomitant use of vonoprazan and rifabutin due to decreased plasma concentrations of vonoprazan, which may reduce its efficacy. Vonoprazan is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Vonoprazan exposures are predicted to be 50% lower when coadministered with a moderate CYP3A4 inducer.
Vonoprazan; Amoxicillin; Clarithromycin: (Major) Avoid concomitant use of vonoprazan and rifabutin due to decreased plasma concentrations of vonoprazan, which may reduce its efficacy. Vonoprazan is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Vonoprazan exposures are predicted to be 50% lower when coadministered with a moderate CYP3A4 inducer. (Major) The combination of rifabutin and clarithromycin should be avoided. Clarithromycin is a substrate and inhibitor of CYP3A4, and rifabutin is a substrate and inducer of CYP3A4. The metabolism of rifabutin is inhibited by clarithromycin, possibly through inhibition of CYP3A4. Inhibition of rifabutin metabolism results in significant increases in rifabutin serum concentrations and adverse reactions. Also, rifabutin increases the metabolism of clarithromycin resulting in significant decreases in clarithromycin concentrations thereby reducing the antimicrobial efficacy of clarithromycin. As compared with the plasma concentration obtained with clarithromycin monotherapy, the clarithromycin plasma concentration was reduced by 63% when rifabutin 600 mg daily was coadministered. Specifically, as monotherapy, the mean serum clarithromycin concentration was 5.4 +/- 2.1 mcg/ml. The mean serum clarithromycin concentration was 2 +/- 1.5 mcg/ml when given in combination with rifabutin. The mean serum concentrations of 14-OH clarithromycin were similar between the two groups.
Vorapaxar: (Moderate) Use caution during concurrent use of vorapaxar and rifabutin. Decreased serum concentrations of vorapaxar and thus decreased efficacy are possible when vorapaxar, a CYP3A4 substrate, is coadministered with rifabutin, a CYP3A inducer.
Voriconazole: (Contraindicated) Concurrent administration of rifabutin and voriconazole is contraindicated. In one study, the maximum plasma concentration (Cmax) and systemic exposure (AUC) of voriconazole were decreased by an average of 67% and 79%, respectively, when given with rifabutin. Another study, found concurrent administration caused the Cmax and AUC of rifabutin to be increased by an average of 3-times and 4-times, respectively. Rifabutin induces the CYP2C9, CYP2C19 and CYP3A4 metabolism of voriconazole. Voriconazole inhibits the CYP3A4 metabolism of rifabutin.
Voxelotor: (Major) Avoid coadministration of voxelotor and rifabutin as concurrent use may decrease voxelotor exposure and lead to reduced efficacy. If coadministration is unavoidable, increase voxelotor dosage to 2,000 mg PO once daily in patients 12 years and older. In patients 4 to 11 years old, weight-based dosage adjustments are recommended; consult product labeling for specific recommendations. Voxelotor is a substrate of CYP3A; rifabutin is a moderate CYP3A inducer. Coadministration of voxelotor with a moderate CYP3A inducer is predicted to decrease voxelotor exposure by up to 24%.
Warfarin: (Moderate) Closely monitor the INR if coadministration of warfarin with rifamycins is necessary as concurrent use may decrease the exposure of warfarin leading to reduced efficacy. Rifamycins may induce the hepatic metabolism of warfarin through induction of CYP3A4, CYP2C9, and CYP1A2. A 2- to 3-fold increase in the daily dose of warfarin may be needed within a week of starting rifamycins to maintain appropriate anticoagulation. Once the rifamycin is discontinued, the dose of warfarin will need to be decreased.
Zanubrutinib: (Major) Avoid concurrent use of zanubrutinib and rifabutin due to the risk of decreased zanubrutinib exposure which may reduce its efficacy. If concomitant use is necessary, increase the zanubrutinib dose to 320 mg twice daily and monitor response. Resume the previous dose of zanubrutinib if rifabutin is discontinued. Zanubrutinib is a CYP3A substrate and rifabutin is a moderate CYP3A inducer. Concomitant use with rifabutin decreased zanubrutinib exposure by 44%.
Zidovudine, ZDV: (Minor) Rifabutin may accelerate the metabolism of zidovudine. However the effectiveness of zidovudine against HIV does not appear to be altered and no dosage adjustments are required. The CDC currently considers the nucleoside reverse transcriptase inhibitors, including zidovudine, compatible for concomitant use with rifamycins, including rifampin, rifabutin and rifapentine.
Ziprasidone: (Moderate) Ziprasidone is partially metabolized via the hepatic CYP3A4 isoenzyme. A decrease in ziprasidone plasma levels could potentially occur if the drug is used concurrently with inducers of CYP3A4, such as rifabutin. The concurrent use of ziprasidone with carbamazepine, a potent CYP3A4 inducer, causes a 35% decrease in the AUC of ziprasidone.
Zolpidem: (Moderate) It is advisable to closely monitor for reductions in zolpidem efficacy during co-administration of moderate CYP3A4 inducers, such as rifabutin. CYP3A4 is the primary isoenzyme responsible for zolpidem metabolism, and there is evidence of significant decreases in systemic exposure and pharmacodynamic effects of zolpidem during co-administration of rifampin, a potent CYP3A4 inducer.
Rifabutin appears to inhibit DNA-dependent RNA polymerase in susceptible strains of E. coli and B. subtilis, thereby suppressing RNA synthesis. It is unknown if this mechanism is responsible for activity against M. avium or M. intracellulare. There is also some evidence that it interferes with DNA synthesis in M. tuberculosis. Rifabutin exhibits bactericidal or bacteriostatic action, depending on the drug concentrations reached within an infected site and the susceptibility of the organism.
In general, the following organisms are susceptible to rifabutin: M. avium-intracellulare and some strains of M. tuberculosis, and M. leprae. Rifabutin has similar in vitro actions to rifampin against gram-positive and gram-negative organisms.
Rifabutin is administered orally. Due to its lipophilicity, it is widely distributed with substantial intracellular accumulation. Lung concentrations are approximately 5-10 times higher than serum concentrations. The half-life averages 45 hours. With multiple dosing, systemic concentrations decreased by 38%, but the elimination half-life remained the same. The primary metabolites are 31-hydroxy and 25-O-desacetyl rifabutin. The latter compound exhibits comparable activity to the parent drug, contributing about 10% to the total antimicrobial action. Approximately 53% of a dose is excreted in the urine, primarily as metabolites, and 5% through biliary clearance. Approximately 30% is excreted in the feces.
Affected cytochrome P450 isoenzymes and drug transporters: CYP3A4
Rifabutin may be expected to have a similar effect on some drugs that are affected by coadministration with rifampin. Rifabutin is an inducer and a substrate of the CYP3A4 isoenzyme. Rifabutin appears to be a less potent hepatic enzyme inducer than rifampin; however, the clinical significance of this finding has not been determined. Unlike with rifampin, acetylation of isoniazid by rifabutin is not affected. The overall potency of rifabutin induction is variable among substrates and rifabutin may alter drug metabolizing enzymes in a dose-dependant manner. Additionally, plasma concentrations at standard doses of rifabutin are lower compared to other rifamycins with may explain the lower induction potential clinically.
-Route-Specific Pharmacokinetics
Oral Route
Rifabutin is rapidly absorbed from the GI tract following oral administration. Roughly 53% of a dose is absorbed, but bioavailability is only 12-20% in HIV-positive patients. High-fat content food delays the rate of absorption. Peak plasma concentrations are attained in 1-4 hours.
-Special Populations
Renal Impairment
Patients with renal impairment may require rifabutin dosage adjustments. In patients with mild to moderate renal impairment (CrCl 30-61 ml/min), the AUC was increased by 41% compared to those with CrCl between 61 and 74 ml/min. The AUC was increased by 71% in patients with severe renal impairment (CrCl < 30 ml/min). Dosage adjustments are required in patients with severe renal impairment.
Pediatrics
The pharmacokinetics of rifabutin have not been studied in patients under 18 years of age.
Geriatric
In the elderly (> 70 years), the steady-state pharmacokinetics of rifabutin are more variable.