ALLERGY RELIEF (Generic for ALLERGY)

General Administration Information
For storage information, see the specific product information within the How Supplied section.

Route-Specific Administration

Oral Administration
-Avoid grapefruit, orange, and apple juice before or after drug administration to avoid potential reduction bioavailability.
Oral Solid Formulations
-Tablets or capsules: Administer orally with water. May be administered without regard to meals.
-Orally disintegrating tablets: Dissolve tablets on the tongue then swallow with or without water; do not chew. Administer on an empty stomach. Do not remove from original blister package until the time of administration.

Oral Liquid Formulations
-Oral suspension: Shake well prior to each use. Measure dosage using a calibrated measuring device. Keep in a tightly closed container away from children.

Fexofenadine is a metabolite of terfenadine. Terfenadine has caused QT prolongation and ventricular tachycardias (torsade de pointes) and was withdrawn from the U.S. market after ten years of post-marketing experience. Fexofenadine, however, demonstrated no significant prolongation of the QT interval in 855 pediatric patients who received doses up to 60 mg PO twice daily. In adults, doses up to 400 mg PO twice daily have been studied and were not associated with a significant increase in the QT interval. Although one case report documented ventricular tachycardia associated with QT prolongation during fexofenadine therapy in a patient with a history of prolonged QT interval, there were confounding factors that could offer alternative explanations for the QT lengthening effect.

The most common respiratory adverse reactions associated with fexofenadine include cough (1.9-4%), naso-pharyngitis (<= 2.4%), and rhinorrhea (0.9-2.1%). Infections that were reported during fexofenadine use include upper respiratory tract infection (0.9-4.3%) and otitis media (2.4-3.8%). Fever was reported in 1.9-4.5% of patients <= 11 years in clinical trials; it was not reported in adult trials. In placebo-controlled studies of pediatric patients 6 months to 5 years of age (n = 534 fexofenadine; n = 430 placebo), adverse effects reported with oral suspension or capsule content administration in greater than 2% of patients included pyrexia (3.9% vs. 7% placebo), cough (3.6% vs. 3.3% placebo), otitis media (3.6% vs. 3.3% placebo), rhinorrhea (1.9% vs. 0.9% placebo), and upper respiratory tract infections (1.9% vs. 4% placebo). Adverse reactions reported in greater than 2% of patients in a placebo-controlled study of children 6-11 years old (n = 209 fexofenadine; n = 229 placebo) included upper respiratory tract infection (4.3% vs. 1.7% placebo), cough (3.8% vs. 1.3% placebo), fever (2.4% vs. 0.9% placebo), and otitis media (2.4% vs. 0% placebo).

Although central nervous system (CNS) adverse effects of fexofenadine are less than those associated with first-generation antihistamines, CNS adverse reactions do occur in some patients. Headache (4.8% to 10.3%) is one of the most common adverse reactions associated with fexofenadine in both pediatric and adult patients. Dizziness (2.1%) and drowsiness or fatigue (0.7% to 2.8%) have also been reported. Drowsiness/fatigue was not dose-related and was reported more frequently in infants and children than in adolescents and adults. Events that have been reported during controlled clinical trials involving seasonal allergic rhinitis and chronic spontaneous urticaria patients with frequencies less than 1%, similar to placebo, and have rarely been reported during postmarketing surveillance of fexofenadine include: insomnia, nervousness (restlessness), and sleep disorders or paranoia.

In clinical trials, the most common gastrointestinal (GI) adverse reaction associated with fexofenadine was vomiting (4.2-12%), and it was only reported in the 6 months to 5 years age group. Vomiting was reported in 12% of subjects receiving fexofenadine 30 mg/day and 4.2% of those receiving 60 mg/day, with an incidence of 8.6% in the placebo group. Diarrhea (2.8-3.7% vs. 2.6% placebo) was also reported in this age group. Dyspepsia (4.7% vs. 4.4% placebo) was reported in clinical trials of patients 12 years of age and older.

In rare cases during fexofenadine use, rash (unspecified), urticaria, pruritus, and hypersensitivity reactions (anaphylactoid reactions) with manifestations such as angioedema, chest tightness/chest pain (unspecified), dyspnea, flushing and systemic anaphylaxis have been reported.

Adverse reactions reported in greater than 2% of patients in a placebo-controlled study in children 6-11 years old included accidental injury (2.9%) and pain (unspecified) (2.4%). Other adverse events that have been reported in clinical trials of patients 12 years of age and older include myalgia (2.6% vs. 2.2% placebo), back pain (2.1-2.5% vs. 1.1-1.4% placebo), dysmenorrhea (1.5% vs. 0.3% placebo), and unspecified pain in extremity (2.1% vs. 0% placebo).

Do not use fexofenadine in patients with a history of fexofenadine hypersensitivity. Use with caution in patients with terfenadine hypersensitivity because fexofenadine is an active metabolite of terfenadine.

Fexofenadine Orally Disintegrating Tablets (ODT) contain phenylalanine, a component of aspartame. Each 30 mg tablet contains 5.3 mg of phenylalanine. Do no use fexofenadine ODT in patients with phenylketonuria.

Although fexofenadine causes less sedation than first-generation antihistamines, drowsiness is experienced by some patients. Patients receiving fexofenadine should not perform activities requiring coordination and concentration, such as gymnastics, riding a bicycle or for older adolescents, operation of vehicles, until they are aware of how this medication affects them. Because the effects of ethanol or other CNS depressants may be additive with antihistamines, counsel adolescents who could be at risk for ethanol intoxication to avoid the use of alcohol while taking fexofenadine.

Use fexofenadine cautiously in patients with renal impairment (CrCl < 80 mg/min/1.73m2) or renal failure; a lower initial dose should be used. Peak plasma concentrations are higher and clearance is slower in patients with renal impairment compared to patients with normal renal function. Peak plasma concentrations in dialysis patients are also significantly higher; the detailed effects of dialysis on fexofenadine pharmacokinetics is unknown.

Description: Fexofenadine is an H1-receptor antagonist. It is the active metabolite of another H1-antagonist, terfenadine. Fexofenadine is classified as a new generation antihistamine (sometimes called a second-generation or non-sedating antihistamine). Like other agents in its class, it causes less sedation than first-generation antihistamines (e.g., diphenhydramine). Fexofenadine, loratadine, and desloratidine appear to cause less sedation than cetirizine. Although fexofenadine is a metabolite of terfenadine, which has been associated with QT prolongation and ventricular tachycardias (torsades de pointes), fexofenadine demonstrated no significant prolongation of the QT interval in 855 pediatric patients who received doses up to 60 mg PO twice daily. In adults, doses up to 800 mg/day have been studied and were not associated with a significant increase in the QT interval. Although one case report documented ventricular tachycardia associated with QT prolongation during fexofenadine therapy in a patient with a history of prolonged QT interval, there were confounding factors that could offer alternative explanations for the QT lengthening effect. Fexofenadine is effective in the treatment of seasonal allergic rhinitis and chronic spontaneous urticaria. Clinical guidelines recommend the use of new generation antihistamines, including fexofenadine, over first-generation antihistamines for the treatment of allergic rhinitis in patients with asthma. Fexofenadine is FDA-approved for use in pediatric patients 6 months of age and older.

For the management of symptoms of perennial allergies and seasonal allergies, including allergic rhinitis:
Oral dosage (oral suspension containing fexofenadine 30 mg per 5 mL):
Children 2 to 11 years: 30 mg PO twice daily.
Children and Adolescents 12 years and older: 60 mg PO twice daily.
Oral dosage (orally disintegrating tablets [ODT]):
Children 6 to 11 years: 30 mg PO twice daily; place on the tongue and allow to disintegrate.
Children and Adolescents 12 years and older: 60 mg PO twice daily; place on the tongue and allow to disintegrate.
Oral dosage (tablets and capsules):
Children 6 to 11 years: 30 mg PO twice daily. During controlled trials of patients 6 to 11 years of age, 60 mg twice daily was not more beneficial than 30 mg twice daily.
Children and Adolescents 12 years and older: 60 mg PO twice daily. Alternatively, 180 mg PO once daily.

For the treatment of chronic spontaneous urticaria:
Oral dosage (oral suspension containing fexofenadine 30 mg per 5 mL):
Infants and Children 6 months and up to 2 years: 15 mg PO twice daily.
Children 2 to 11 years: 30 mg PO twice daily.
Oral dosage (orally disintegrating tablets [ODT]):
Children 6 to 11 years: 30 mg PO twice daily; place on the tongue and allow to disintegrate.
Oral dosage (tablets and capsules):
Children 6 to 11 years: 30 mg PO twice daily.
Children and Adolescents 12 years and older: 60 mg PO twice daily. Alternatively, 180 mg PO once daily.

Maximum Dosage Limits:
-Neonates
Safety and efficacy have not been established.
-Infants
Less than 6 months: Safety and efficacy have not been established.
6 months and older: 30 mg/day PO.
-Children
Less than 2 years: 30 mg/day PO.
2 to 11 years: 60 mg/day PO.
12 years: 180 mg/day PO if given once daily; 120 mg/day if given in 2 divided doses.
-Adolescents
180 mg/day PO if given once daily; 120 mg/day if given in 2 divided doses.

Patients with Hepatic Impairment Dosing
No dosage adjustment is recommended. The pharmacokinetics of fexofenadine are not substantially affected by hepatic disease.

Patients with Renal Impairment Dosing
CrCl >= 80 ml/min/1.73m2: No adjustment necessary.
CrCl 11-80 ml/min/1.73m2: Reduce the starting dose to once daily administration as follows:
Infants >= 6 months and Children < 2 years: 15 mg PO once daily.
Children 2-11 years old: 30 mg PO once daily.
Children and Adolescents >= 12 years: 60 mg PO once daily.
CrCl <= 10 ml/min/1.73m2:
Infants and Children < 12 years: Dosage recommendations are not available.
Children and Adolescents >= 12 years: Although not included in the FDA-approved label, some experts recommend 30 mg PO daily.

Intermittent hemodialysis
Although not included in the FDA-approved label, some experts recommend 30 mg PO daily for children and adolescents >= 12 years; dosing for other age groups is not available. The effect of hemodialysis on the removal of fexofenadine is unknown. After terfenadine oral administration, hemodialysis did not effectively remove fexofenadine (the major active metabolite of terfenadine) from blood (up to 1.7% was removed).

*non-FDA-approved indication

Monograph content under development

Mechanism of Action: Fexofenadine is an antihistamine with selective H1-receptor antagonist activity. Similar to other H1-blockers, fexofenadine does not prevent the release of histamine as do cromolyn and nedocromil, but competes with free histamine for binding at the H1-receptor. This competitive antagonism blocks the effects of histamine on H1-receptors in the GI tract, uterus, large blood vessels, and bronchial smooth muscle. Blockade of H1-receptors also suppresses the formation of edema, flare, and pruritus that result from histaminic activity. Unlike first generation H1-blockers (e.g., diphenhydramine), fexofenadine does not cross the blood-brain barrier and does not exert anticholinergic or alpha-1-antagonist effects in animal studies.

In patients with allergic rhinitis, the inflammatory response plays a prominent role in the development of nasal obstruction and involves a number of mediators. Initial release of histamine from mast cells is followed by late-phase reactions involving a number of other cells, such as fibroblasts, epithelial cells, neutrophils, eosinophils (especially in conditions with raised IgE levels), macrophages, platelets, and lymphocytes. Cell adhesion can also be part of the inflammatory process. In vitro, fexofenadine decreases the release of many of these mediators (e.g. eosinophils, interleukin-6, interleukin-8, granulocyte-macrophage colony-stimulating factor) from a variety of cell types (e.g. epithelial, fibroblast, basophils and mast cells) at concentrations close to those achieved at clinical dosages.

Pharmacokinetics: Fexofenadine is administered orally. The onset of antihistamine effect (evaluated by wheal and flare studies) occurs within 1-2 hours and peaks 2-3 hours after administration. The effect lasts for at least 8 hours in pediatric patients and persists for up to 12 hours in adults. Protein binding ranges from 60-70%; fexofenadine is primarily bound to albumin and alpha-1-acid glycoprotein. In radiolabeled studies, approximately 80% and 11% of a dose was recovered in the feces and urine, respectively. Approximately 5% of the total administered dose is hepatically metabolized. Because the absolute bioavailability has not been determined, it is unknown if the fecal component represents unabsorbed drug or biliary excretion of the drug. Therefore, it is unknown if either renal excretion and/or metabolism plays a significant role in systemic drug elimination. The mean elimination half-life is approximately 14.4 hours in adult volunteers. Unlike many other drugs, fexofenadine clearance is somewhat slower in pediatric patients compared to adults.

Affected cytochrome P450 isoenzymes and drug transporters: P-glycoprotein (P-gp) and organic anion transporting peptide (OATP)
Fexofenadine is a substrate for P-glycoprotein (P-gp) and organic anion transporting peptide (OATP) transport.


-Route-Specific Pharmacokinetics
Oral Route
Fexofenadine is rapidly absorbed. The mean time to maximum plasma concentration after oral administration of capsules or oral suspension is 2.6 hours and 1 hour, respectively. The mean time to maximum plasma concentrations of the orally disintegrating tablet (ODT) formulation is 2 hours post-dose. The absolute bioavailability of fexofenadine is unknown. Administration of the ODT formulation with a high fat-meal decreases the AUC and Cmax by about 40% and 60%, respectively, and Tmax is delayed by 2 hours. Therefore, fexofenadine ODT should be taken on an empty stomach. The bioavailability of the ODT formulation is comparable whether given with or without water. When the tablet is given with a high fat meal, the AUC and Cmax are decreased by approximately 20%. Mixing capsule contents with applesauce has no significant effect on the PK parameters. Administration of the oral suspension and a high fat meal decreases the AUC and Cmax by approximately 30% and 47% respectively. The tablets, capsule, and oral suspension may be given with food. Fexofenadine (Allegra) suspension containing 30 mg is bioequivalent to Allegra 30 mg tablets.


-Special Populations
Pediatrics
Infants and Children
Fexofenadine 15 mg given to patients 6 months to < 2 years and 30 mg given to children 2-11 years produces comparable plasma exposure to that seen in adults receiving a 60 mg dose. A population pharmacokinetic analysis was performed using data from 90 treatment exposures in children (6 months to 12 years) and 269 treatment exposures from adults. Estimated oral clearances were on average 36% and 44% lower in children 2-5 years and 6-12 years, respectively, compared to adults. In a double-blind, two-way crossover study, 14 children (mean age 9.8 +/- 1.8 years) received a single dose of fexofenadine 30 mg and 60 mg 1 week apart. The following mean pharmacokinetic parameters were calculated for the 30 mg dose: Volume of distribution (Vd) = 5.4 +/- 0.7 L/kg, clearance (Cl) = 14.4 +/- 2 mL/min/kg, and terminal elimination half-life (t1/2) = 18.3 +/- 2 hours. The following parameters were calculated for the 60 mg dose: Vd = 5.8 +/- 0.7 L/kg, CL = 18.4 +/- 2.4 mL/kg/min, and terminal elimination t1/2 = 17.6 +/- 1 hours.

Hepatic Impairment
The pharmacokinetics of fexofenadine do not appear to be altered by hepatic disease. The pharmacokinetics of fexofenadine hydrochloride in adult patients with hepatic disease did not differ substantially from that observed in healthy subjects.

Renal Impairment
The pharmacokinetics of fexofenadine are altered by renal disease; dosage adjustments are recommended for patients with renal impairment. Peak plasma concentrations were 87% and 111% greater in adult patients with mild (CrCl 41-80 mL/min) to severe (CrCl 11-40 mL/min) renal impairment, respectively. Mean elimination half-lives were 59% and 72% longer, respectively, than in healthy adult volunteers. Peak plasma concentrations in dialysis patients (CrCl <= 10 mL/min) were 82% greater and half-life was 31% longer than in healthy adult volunteers. The effect of hemodialysis on the removal of fexofenadine is unknown. After terfenadine oral administration, hemodialysis did not effectively remove fexofenadine (the major active metabolite of terfenadine) from blood (up to 1.7% was removed).