Famciclovir is an oral antiviral agent with activity against alpha herpes virus. It is FDA-approved for use in immunocompetent patients to treat herpes zoster (shingles), treat or suppress recurrent genital herpes, and treat recurrent herpes labialis (cold sores). It is also approved for use in patients with HIV to treat recurrent orolabial or genital herpes. Famciclovir is a prodrug for the active metabolite penciclovir. The spectrum of activity of penciclovir is similar to acyclovir, but penciclovir has a longer duration of action due to a longer intracellular half-life; thus, orally administered famciclovir can be dosed less frequently than oral acyclovir. Dose reductions are advised for patients with renal impairment, as cases of acute renal failure have been reported in patients with underlying renal disease who received inappropriately high doses of famciclovir for their level of renal function. Famciclovir was FDA-approved in 1994.
General Administration Information
For storage information, see the specific product information within the How Supplied section.
Route-Specific Administration
Oral Administration
-May be administered without regard to meals.
During clinical trials, episodes of headache and migraine were experienced by 8.5 to 39.3% and 0.2 to 3.1% of famciclovir recipients, respectively. Other neurologic adverse events included fatigue (0.6 to 4.8%) and paresthesias (0.9 to 2.6%). Cases of seizures, confusion, delirium, disorientation, dizziness, drowsiness, and hallucinations have been noted during postmarketing use. Due to the voluntary nature of postmarketing reports, neither a frequency nor a definitive causal relationship can be established.
During clinical trials for genital herpes suppression, 0.2% of famciclovir recipients and 0.3% of patients receiving placebo experienced serum creatinine greater than 1.5-times upper limits of normal. Patients with underlying renal dysfunction have developed acute renal failure after receiving inappropriately high doses of famciclovir. Dosage reduction is recommended for patients with preexisting renal impairment.
Gastrointestinal and digestive adverse events have been associated with famciclovir treatment. During clinical trials, nausea (2.2% to 12.5%), vomiting (0.7% to 5%), abdominal pain (0.2% to 7.9%), diarrhea (1.6% to 9%), and flatulence (0.2% to 4.8%) were reported. Additionally, cases of hyperamylasemia (greater than 1.5-times upper limit of normal, ULN) and elevated lipase concentrations (greater than 1.5-times ULN) were reported in 1.5% and 4.9% of famciclovir recipients, respectively.
During clinical trials, rash (unspecified) and pruritus were observed in 0.4% to 3.3% and 2.2% to 3.7% of famciclovir recipients, respectively. Other adverse events reported during postmarketing use of the drug include urticaria, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, hypersensitivity vasculitis, anaphylactic shock, anaphylactoid reactions, and angioedema. Due to the voluntary nature of postmarketing reports, neither a frequency nor a definitive causal relationship can be established.
Hematologic adverse events observed in patients receiving treatment with famciclovir for genital herpes suppression include anemia (0.1%, less than 0.8-times lower limits of normal, LLN), leukopenia (1.3%, less than 0.75-times LLN), and neutropenia (3.2%, less than 0.8-times LLN). Cases of thrombocytopenia have been noted during postmarketing use of the drug. Due to the voluntary nature of postmarketing reports, neither a frequency nor a definitive causal relationship can be established.
Cases of hyperbilirubinemia (greater than 1.5-times upper limit of normal, ULN) and elevated hepatic enzymes (greater than 2-times ULN) were observed in 1.9% and 2.3% to 3.2%, respectively, of patients receiving famciclovir during clinical trials for genital herpes suppression. Additionally, famciclovir has been associated with the development of cholestatic jaundice during postmarketing use. Due to the voluntary nature of postmarketing reports, neither a frequency nor a definitive causal relationship can be established.
During clinical trials, dysmenorrhea was reported by 0.4% to 7.6% of famciclovir recipients and 0.6% to 6.3% of patients receiving placebo.
Famciclovir has been associated with the development of palpitations during postmarketing use.
Famciclovir is contraindicated for use in patients with famciclovir hypersensitivity or penciclovir hypersensitivity.
Renal clearance of penciclovir (the active metabolite of famciclovir) is decreased in patients with renal impairment. Famciclovir dose reductions are recommended for patients with creatinine clearance values less than 60 mL/minute, including patients with renal failure receiving dialysis. Acute renal failure has been reported in patients receiving inappropriately high doses of famciclovir for their level of renal function. Geriatric patients, aged 65 years and older, may also have reduced rates of drug clearance which, in part, may be due to changes in renal function.
The safety and efficacy of famciclovir have not been established in patients with ophthalmic zoster, patients with first episode genital herpes, Black patients with recurrent genital herpes, or in patients with immunosuppression (other than HIV patients to treat recurrent orolabial or genital herpes).
Available data from pharmacovigilance reports have not associated the use of famciclovir during pregnancy with any increased risk for major birth defects, miscarriages, or adverse maternal or fetal outcomes. Similarly, animal reproduction studies have not identified any evidence of teratogenicity. However, there are fetal risks associated with untreated herpes simplex virus during pregnancy. Administer famciclovir during pregnancy when the benefits to the mother outweigh risks to the fetus. To monitor maternal-fetal outcomes of pregnant patients exposed to famciclovir, healthcare providers are encouraged to report exposures and outcomes to the manufacturers Adverse Events reporting line by calling 888-669-6682.
It is not known if famciclovir or penciclovir, the active metabolite, are excreted into human milk, affect a breast-fed infant, or affect milk production. There are no published data with famciclovir during breast-feeding; thus, other drugs may be preferred. Acyclovir and valacyclovir may be potential alternatives to consider during breast-feeding. However, patient factors, local susceptibility patterns, and specific microbial susceptibility should be assessed before choosing an alternative agent. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally ingested drug, healthcare providers are encouraged to report the adverse effect to the FDA.
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: herpes simplex virus type 1, herpes simplex virus type 2, varicella-zoster virus
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: Epstein-Barr virus
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 herpes zoster (shingles) infection:
NOTE: The use of famciclovir was studied in immunocompetent adults with uncomplicated herpes zoster who received treatment within 72 hours of rash onset. Efficacy has not been established when initiated more than 72 hours after the onset of rash.
NOTE: Safety and efficacy have not been established in patients with ophthalmic zoster.
-for the treatment of herpes zoster (shingles) infection in immunocompetent patients:
Oral dosage:
Adults: 500 mg PO every 8 hours for 7 days, beginning as soon as possible after diagnosis, preferably within 48 hours of rash onset. The treatment of acute herpes zoster (shingles) with famciclovir will significantly decrease the incidence and duration of postherpetic neuralgia.
Adolescents*: 500 mg PO every 8 hours for 7 days. Initiate as soon as possible after diagnosis, preferably within 48 hours of rash onset.
-for the treatment of herpes zoster (shingles) infection in persons living with HIV*:
Oral dosage:
Adults: 500 mg PO every 8 hours for 7 to 10 days for localized infection; a longer duration of therapy may be required if lesions are slow to resolve. For those with extensive cutaneous lesions or visceral involvement, use as stepdown therapy after IV acyclovir to complete a 10- to 14-day course.
Adolescents: 500 mg PO every 8 hours for 7 to 10 days for localized infection; a longer duration of therapy may be required if lesions are slow to resolve. For those with extensive cutaneous lesions or visceral involvement, use as stepdown therapy after IV acyclovir to complete a 10- to 14-day course.
For the treatment of herpes simplex virus infection including herpes genitalis and herpes labialis:
-for the treatment of initial episode* of herpes genitalis in immunocompetent patients:
Oral dosage:
Adults: 250 mg PO every 8 hours for 7 to 10 days or until clinical resolution.
Children weighing 45 kg or more and Adolescents: 250 mg PO every 8 hours for 7 to 10 days or until clinical resolution.
-for the treatment of initial episode* of herpes genitalis in persons living with HIV:
Oral dosage:
Adults: 500 mg PO every 12 hours for 7 to 10 days or until clinical resolution.
Adolescents: 500 mg PO every 12 hours for 7 to 10 days or until clinical resolution.
-for the treatment of recurrent herpes genitalis in immunocompetent patients:
Oral dosage:
Adults: 1,000 mg PO every 12 hours for 1 day; 500 mg PO once, then 250 mg PO every 12 hours for 2 days; or 125 mg PO every 12 hours for 5 days. Treatment should begin at the first sign or symptom. Efficacy has not been established when treatment is initiated more than 6 hours after onset of symptoms or lesion formation.
Children* weighing 45 kg or more and Adolescents*: 1,000 mg PO every 12 hours for 1 day; 500 mg PO once, then 250 mg PO every 12 hours for 2 days; or 125 mg PO every 12 hours for 5 days. Treatment should begin at the first sign or symptom. Efficacy has not been established when treatment is initiated more than 6 hours after onset of symptoms or lesion formation.
-for the treatment of recurrent herpes genitalis in persons living with HIV:
Oral dosage:
Adults: 500 mg PO every 12 hours for 5 to 10 days. Treatment should begin at the first sign or symptom. Efficacy has not been established when treatment is initiated more than 48 hours after onset of symptoms or lesion formation.
Adolescents*: 500 mg PO every 12 hours for 5 to 10 days. Treatment should begin at the first sign or symptom. Efficacy has not been established when treatment is initiated more than 48 hours after onset of symptoms or lesion formation.
-for the treatment of recurrent herpes labialis in immunocompetent patients:
Oral dosage:
Adults: 1,500 mg PO as a single dose at the first sign or symptom.
Adolescents*: 1,500 mg PO as a single dose at the first sign or symptom.
Children 12 years*: Not approved for use in patients younger than 18 years of age. Safety and efficacy for the treatment of recurrent herpes labialis in children was evaluated during an open-label, single-arm study. Pediatric patients were enrolled if between the ages of 12 and 17 years and weighed 40 kg or more. Within 24 hours of symptom onset, 43 pediatric patients were administered a single 1,500 mg dose (median time to initiation was 21 hours). Comparing the study results with an adult study found the safety profiles to be similar; however, efficacy (defined as the median time to healing) was lower in the pediatric population. In pediatric patients, the median time to healing of non-aborted lesions was 5.9 days compared with 4.4 days for adult. It is important to note that in the adult study, treatment was initiated within 1 hours of symptom onset.
-for the treatment of recurrent herpes labialis in persons living with HIV:
Oral dosage:
Adults: 500 mg PO every 12 hours for 5 to 10 days at the first sign or symptom. Efficacy has not been established when treatment is initiated more than 48 hours after onset of symptoms or lesion formation.
Adolescents*: 500 mg PO every 12 hours for 5 to 10 days at the first sign or symptom. Efficacy has not been established when treatment is initiated more than 48 hours after onset of symptoms or lesion formation.
For herpes genitalis prophylaxis or secondary genital herpes simplex infection prophylaxis (i.e., long-term suppressive therapy) in patients with frequent or severe recurrences:
-for long-term suppressive therapy of recurrent herpes genitalis in immunocompetent patients:
Oral dosage:
Adults: 250 mg PO every 12 hours. The safety and efficacy beyond 1 year have not been established.
Children* weighing 45 kg or more and Adolescents*: 250 mg PO every 12 hours. The safety and efficacy beyond 1 year have not been established.
-for long-term suppressive therapy of recurrent herpes genitalis in persons living with HIV*:
Oral dosage:
Adults: 500 mg PO every 12 hours. Although safety and efficacy beyond 1 year have not been established, guidelines suggest suppressive therapy may be continued indefinitely (without regard to CD4 count). A review of the continued need should be conducted annually.
Children weighing 45 kg or more and Adolescents: 500 mg PO every 12 hours. Although safety and efficacy beyond 1 year have not been established, guidelines suggest suppressive therapy may be continued indefinitely (without regard to CD4 count). A review of the continued need should be conducted annually.
For the adjunctive treatment of Bell's palsy* in combination with steroids:
Oral dosage:
Adults: 250 mg PO every 8 hours for 5 to 7 days in combination with an oral corticosteroid. Clinical practice guidelines suggest an antiviral plus oral corticosteroid within 72 hours of symptom onset to modestly increase probability of functional facial nerve recovery.
For the treatment of varicella (chickenpox) infection*:
-for the treatment of uncomplicated varicella (chickenpox) infection* in immunocompromised patients:
Oral dosage:
Adults: 500 mg PO every 8 hours for 5 to 7 days. Initiate therapy at the first sign of symptoms (i.e., within 24 hours).
Adolescents: 500 mg PO every 8 hours for 5 to 7 days. Initiate therapy at the first sign of symptoms (i.e., within 24 hours).
-for the treatment of severe or complicated varicella (chickenpox) infection* in immunocompromised patients as stepdown therapy from IV acyclovir:
Oral dosage:
Adults: 500 mg PO every 8 hours for a total treatment course of 7 to 10 days.
Adolescents: 500 mg PO every 8 hours for a total treatment course of 7 to 10 days.
For the treatment of herpes simplex ocular infection*, including herpes simplex virus epithelial keratitis*, herpes simplex virus stromal keratitis*, and herpes simplex virus endothelial keratitis*:
-for the treatment of dendritic epithelial keratitis:
Oral dosage:
Adults: 250 mg PO every 12 hours for 7 to 10 days.
-for the treatment of geographic epithelial keratitis:
Oral dosage:
Adults: 500 mg PO every 12 hours for 14 to 21 days.
-for the treatment of non-necrotizing stromal keratitis:
Oral dosage:
Adults: 250 mg PO once or twice daily plus topical ophthalmic steroid for at least 10 weeks.
-for the treatment of necrotizing stromal keratitis:
Oral dosage:
Adults: 500 mg PO 2 to 3 times daily for 7 to 10 days plus topical ophthalmic steroid, then 250 mg PO every 12 hours for the duration of topical ophthalmic steroid use.
-for the treatment of endothelial keratitis:
Oral dosage:
Adults: 250 to 500 mg PO every 12 hours for 7 to 10 days plus topical ophthalmic steroid, then 250 mg PO every 12 hours for the duration of topical ophthalmic steroid use.
For the treatment of herpes zoster ocular infection (herpes zoster ophthalmicus), including viral conjunctivitis*:
-for the treatment of herpes zoster ocular infection in immunocompetent patients*:
Oral dosage:
Adults: 500 mg PO every 8 hours for 7 days. Initiate therapy within 48 to 72 hours of rash onset.
Children and Adolescents 12 to 17 years: 500 mg PO every 8 hours for 7 days. Initiate therapy within 48 to 72 hours of rash onset.
-for the treatment of herpes zoster ocular infection in immunocompromised patients*:
NOTE: Oral therapy can be considered for those who are not severely immunosuppressed.
Oral dosage:
Adults: 500 mg PO every 8 hours for 7 to 14 days. Initiate therapy within 48 to 72 hours of rash onset.
Children and Adolescents 12 to 17 years: 500 mg PO every 8 hours for 7 to 14 days. Initiate therapy within 48 to 72 hours of rash onset.
Maximum Dosage Limits:
-Adults
2,000 mg per day PO for single-day therapy or 1,500 mg per day PO for multiple-day therapy.
-Geriatric
2,000 mg per day PO for single-day therapy or 1,500 mg per day PO for multiple-day therapy.
-Adolescents
Safety and efficacy have not been established; however, doses up to 2,000 mg per day PO for single-day therapy or 1,500 mg per day PO for multiple-day therapy have been used off-label.
-Children
weight 45 kg or more: Safety and efficacy have not been established; however, doses up to 2,000 mg per day PO for single-day therapy or 1,000 mg per day PO for multiple-day therapy have been used off-label.
weight less than 45 kg: Safety and efficacy have not been established.
-Infants
Safety and efficacy have not been established.
-Neonates
Safety and efficacy have not been established.
Patients with Hepatic Impairment Dosing
No dosage adjustment is recommended for patients with well-compensated hepatic impairment. The pharmacokinetics of penciclovir (the active moiety of famciclovir) have not been evaluated in patients with severe uncompensated hepatic impairment.
Patients with Renal Impairment Dosing
Treatment of herpes zoster:
CrCl 60 mL/minute or more: no dosage adjustment needed.
CrCl 40 to 59 mL/minute: 500 mg PO every 12 hours.
CrCl 20 to 39 mL/minute: 500 mg PO every 24 hours.
CrCl less than 20 mL/minute: 250 mg PO every 24 hours.
Acute treatment of recurrent herpes genitalis in immunocompetent patients:
CrCl 60 mL/minute or more: no dosage adjustment needed.
CrCl 40 to 59 mL/minute: 500 mg PO every 12 hours for 1 day.
CrCl 20 to 39 mL/minute: 500 mg PO single dose.
CrCl less than 20 mL/minute: 250 mg PO single dose.
Acute treatment of recurrent herpes labialis in immunocompetent patients:
CrCl 60 mL/minute or more: no dosage adjustment needed.
CrCl 40 to 59 mL/minute: 750 mg PO single dose.
CrCl 20 to 39 mL/minute: 500 mg PO single dose.
CrCl less than 20 mL/minute: 250 mg PO single dose.
Herpes genitalis prophylaxis in immunocompetent patients:
CrCl 40 mL/minute or more: no dosage adjustment needed.
CrCl 20 to 39 mL/minute: 125 mg PO every 12 hours.
CrCl less than 20 mL/minute: 125 mg PO every 24 hours.
Recurrent orolabial and genital herpes simplex in HIV-infected patients:
CrCl 40 mL/minute or more: no dosage adjustment needed.
CrCl 20 to 39 mL/minute: 500 mg PO every 24 hours.
CrCl less than 20 mL/minute: 250 mg PO every 24 hours.
Intermittent hemodialysis
For recurrent genital herpes or herpes labialis in immunocompetent patients, give 250 mg PO as a single dose following dialysis session. For herpes genitalis prophylaxis in immunocompetent patients, give 125 mg PO after each dialysis session. For herpes zoster and recurrent herpes simplex virus infection in HIV-infected patients, give 250 mg PO after each dialysis session.
*non-FDA-approved indication
Measles Virus; Mumps Virus; Rubella Virus; Varicella Virus Vaccine, Live: (Major) If possible, discontinue famciclovir at least 24 hours before administration of the varicella-zoster virus vaccine, live. Also, do not administer famciclovir for at least 14 days after vaccination. Concurrent administration of any of the varicella-zoster virus vaccines (Zostavax, Varivax, ProQuad) with antiviral medications known to be effective against varicella zoster virus has not been evaluated. Therefore, when possible, a washout period between the use of the antiviral medication and the vaccines is recommended. Refer to the most recent Center for Disease control guidance if concurrent use is necessary.
Probenecid: (Moderate) Probenecid undergoes both renal tubular secretion and renal tubular reabsorption. Concomitant administration of probenecid with famciclovir may impair clearance of the active metabolite, penciclovir. Probenecid should be avoided during therapy with famciclovir.
Probenecid; Colchicine: (Moderate) Probenecid undergoes both renal tubular secretion and renal tubular reabsorption. Concomitant administration of probenecid with famciclovir may impair clearance of the active metabolite, penciclovir. Probenecid should be avoided during therapy with famciclovir.
Talimogene Laherparepvec: (Major) Consider the risks and benefits of treatment with talimogene laherparepvec before administering acyclovir or other antivirals to prevent or manage herpetic infection. Talimogene laherparepvec is a live, attenuated herpes simplex virus that is sensitive to acyclovir; coadministration with antiviral agents may cause a decrease in efficacy.
Varicella-Zoster Virus Vaccine, Live: (Major) If possible, discontinue famciclovir at least 24 hours before administration of the varicella-zoster virus vaccine, live. Also, do not administer famciclovir for at least 14 days after vaccination. Concurrent administration of any of the varicella-zoster virus vaccines (Zostavax, Varivax, ProQuad) with antiviral medications known to be effective against varicella zoster virus has not been evaluated. Therefore, when possible, a washout period between the use of the antiviral medication and the vaccines is recommended. Refer to the most recent Center for Disease control guidance if concurrent use is necessary.
Famciclovir is a prodrug for penciclovir, the active compound. Penciclovir has activity against herpes simplex virus types 1 (HSV-1) and 2 (HSV-2) and varicella-zoster virus (VZV). In cells infected with HSV-1, HSV-2, or VZV, the viral thymidine kinase (TK) phosphorylates penciclovir to a monophosphate form. This monophosphate form is then converted by cellular kinases to the active penciclovir triphosphate. In vitro studies show that penciclovir triphosphate selectively inhibits viral DNA polymerase by competing with deoxyguanosine triphosphate. Inhibition of DNA synthesis of virus-infected cells inhibits viral replication.
Penciclovir-resistant HSV-1 and HSV-2 isolates have been isolated in cell culture studies. Resistance of HSV and VZV to penciclovir can result from mutations in the viral TK and DNA polymerase (POL) genes. Mutations in the viral TK may lead to the complete loss of viral TK activity, reduced levels of TK activity, or alterations in the ability of viral TK to phosphorylate the drug. Resistance should be considered in patients who fail to respond or experience recurrent viral shedding during therapy. Cross-resistance has been observed in acyclovir-resistant HSV-1 and HSV-2 isolates with TK and POL mutations and in foscarnet-resistant HSV-1 isolates with POL mutations.
Famciclovir is administered orally. Famciclovir undergoes almost complete deacetylation and oxidation to produce penciclovir and several inactive metabolites (6-deoxy penciclovir, monoacetylated penciclovir, 6-deoxy monoacetylated penciclovir). The conversion of 6-deoxy penciclovir to penciclovir is catalyzed by aldehyde oxidase. Penciclovir has a volume of distribution of 1.08 L/kg, is equally distributed in blood and plasma, and less than 20% bound to plasma proteins. Penciclovir is predominately eliminated unchanged by the kidneys, with about 73% of the oral famciclovir dose eliminated in the urine and 27% excreted in the feces over 72 hours. Penciclovir accounts for 82% and 6-deoxy penciclovir accounts for 7% of the renally excreted drug; little or no famciclovir is detected in the plasma or urine. Plasma elimination half-life is approximately 2 hours. The intracellular half-life of penciclovir triphosphate is approximately 7 hours in varicella zoster virus (VZV)-infected cells, 10 hours in herpes simplex virus type 1 (HSV-1) infected cells, and 20 hours in HSV-2 infected cells. The clinical significance of the intracellular half-life is unknown.
Affected cytochrome P450 isoenzymes: None
Famciclovir is not significantly metabolized by the cytochrome P450 enzyme system. An in vitro study suggests that famciclovir is not an inhibitor of CYP3A4 enzymes.
-Route-Specific Pharmacokinetics
Oral Route
Following oral administration of famciclovir, the absolute bioavailability of penciclovir is approximately 77%. In healthy subjects, the maximum plasma concentration (Cmax) and systemic exposure (AUC) of penciclovir increase proportionally to the famciclovir dose over a range of 125 mg to 1,000 mg. The time to reach maximum concentration (Tmax) is about 45 to 60 minutes, and there is no accumulation of penciclovir after administration of famciclovir 500 mg 3 times daily for 7 days. Administering famciclovir with food (910 Kcal and 26% fat) decreases penciclovir Cmax by approximately 50% and the Tmax is delayed by 1.5 hours; however, there is no effect on the extent of penciclovir systemic availability (AUC). Thus, famciclovir can be taken without regard to meals.
-Special Populations
Hepatic Impairment
Mild or moderate hepatic impairment has no effect on the extent of availability (AUC) of penciclovir. The pharmacokinetics of penciclovir have not been evaluated in patients with severe hepatic impairment.
Renal Impairment
In patients with varying degrees of renal impairment, apparent plasma clearance, renal clearance, and the plasma-elimination rate constant of penciclovir decreases linearly with reductions in renal function after both single and repeated dosing. Famciclovir dosage adjustments are recommended for patients with renal impairment.
Geriatric
Based on cross study comparison, penciclovir AUC is 40% higher and penciclovir renal clearance is 22% lower in geriatric patients (aged 65 to 79 years) as compared with younger subjects. Some of this difference may be due to differences in renal function between the two groups.
Gender Differences
The pharmacokinetics of penciclovir were evaluated in 18 healthy male and 18 healthy female volunteers. Following a single 500 mg dose of famciclovir, the AUC of penciclovir was 9.3 +/- 1.9 mcg x hour/mL in males and 11.1 +/- 2.1 mcg x hour/mL in females. The penciclovir renal clearance was 28.5 +/- 8.9 L/hour and 21.8 +/- 4.3 L/hour in males and females, respectively. These differences were attributed to differences in renal function between the two groups.
Ethnic Differences
A retrospective analysis of the pharmacokinetic parameters of penciclovir in Black and Caucasian adults revealed no significant differences due to race. Data for the analysis was obtained from single and repeated 500 mg doses in healthy volunteers, persons with renal impairment, and persons with hepatic impairment.
Other
Herpes Zoster Patients
In patients with herpes zoster, the penciclovir AUC is approximately 35% higher than in healthy volunteers. This difference may be due to differences in the renal function between the two groups.
Patients with HIV
Following administration of a single 500 mg famciclovir dose to patients with HIV, the pharmacokinetic parameters of penciclovir are comparable to those observed in healthy subjects.