Fexofenadine Hydrochloride (Page 2 of 5)

6.2 Postmarketing Experience

In addition to the adverse reactions reported during clinical studies and listed above, the following adverse events have been identified during post-approval use of fexofenadine hydrochloride. Because these events are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Events that have been reported rarely during postmarketing experience include: insomnia, nervousness, sleep disorders or paroniria, and hypersensitivity reactions (including anaphylaxis, urticaria, angioedema, chest tightness, dyspnea, flushing, pruritus, and rash).

7 DRUG INTERACTIONS

7.1 Antacids

Fexofenadine hydrochloride should not be taken closely in time with aluminum and magnesium containing antacids. In healthy adult subjects, administration of 120 mg of fexofenadine hydrochloride (2 x 60 mg capsule) within 15 minutes of an aluminum and magnesium containing antacid (Maalox®) decreased fexofenadine AUC by 41% and Cmax by 43%.

7.2 Erythromycin and Ketoconazole

Fexofenadine has been shown to exhibit minimal (ca. 5%) metabolism. However, coadministration of fexofenadine hydrochloride with either ketoconazole or erythromycin led to increased plasma concentrations of fexofenadine in healthy adult subjects. Fexofenadine had no effect on the pharmacokinetics of either erythromycin or ketoconazole. In 2 separate studies in healthy adult subjects, fexofenadine hydrochloride 120 mg twice daily (240 mg total daily dose) was coadministered with either erythromycin 500 mg every 8 hours or ketoconazole 400 mg once daily under steady-state conditions to healthy adult subjects (n = 24, each study). No differences in adverse events or QTc interval were observed when subjects were administered fexofenadine hydrochloride alone or in combination with either erythromycin or ketoconazole. The findings of these studies are summarized in the following table:

Table 5: Effects on Steady-State Fexofenadine Pharmacokinetics After 7 Days of Coadministration With Fexofenadine Hydrochloride 120 mg Every 12 Hours in Healthy Adult Subjects (n = 24)
Concomitant Drug CmaxSS (Peak plasma concentration) AUCss(0-12h) (Extent of systemic exposure)
Erythromycin (500 mg every 8 hrs) +82% +109%
Ketoconazole (400 mg once daily) +135% +164%

The changes in plasma levels were within the range of plasma levels achieved in adequate and well-controlled clinical trials.

The mechanism of these interactions has been evaluated in in vitro, in situ , and in vivo animal models. These studies indicate that ketoconazole or erythromycin coadministration enhances fexofenadine gastrointestinal absorption. This observed increase in the bioavailability of fexofenadine may be due to transport-related effects, such as p-glycoprotein. In vivo animal studies also suggest that in addition to enhancing absorption, ketoconazole decreases fexofenadine gastrointestinal secretion, while erythromycin may also decrease biliary excretion.

7.3 Fruit Juices

Fruit juices such as grapefruit, orange and apple may reduce the bioavailability and exposure of fexofenadine. This is based on the results from 3 clinical studies using histamine induced skin wheals and flares coupled with population pharmacokinetic analysis. The size of wheal and flare were significantly larger when fexofenadine hydrochloride was administered with either grapefruit or orange juices compared to water. Based on the literature reports, the same effects may be extrapolated to other fruit juices such as apple juice. The clinical significance of these observations is unknown. In addition, based on the population pharmacokinetics analysis of the combined data from grapefruit and orange juices studies with the data from a bioequivalence study, the bioavailability of fexofenadine was reduced by 36%. Therefore, to maximize the effects of fexofenadine, it is recommended that fexofenadine hydrochloride tablets should be taken with water [see Clinical Pharmacology (12.3) and Dosage and Administration (2.1)].

8 USE IN SPECIFIC POPULATIONS

8.1 Pregnancy

Teratogenic Effects

Pregnancy Category C. There was no evidence of teratogenicity in rats or rabbits at oral doses of terfenadine up to 300 mg/kg (which led to fexofenadine exposures that were approximately 4 and 30 times, respectively, the exposure at the maximum recommended human daily oral dose of 180 mg of fexofenadine hydrochloride based on comparison of AUCs).

In mice, no adverse effects and no teratogenic effects during gestation were observed with fexofenadine hydrochloride at oral doses up to 3730 mg/kg (which led to fexofenadine exposures that were approximately 15 times the exposure at the maximum recommended human daily oral dose of 180 mg of fexofenadine hydrochloride based on comparison of AUCs).

There are no adequate and well controlled studies in pregnant women. Fexofenadine hydrochloride should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Nonteratogenic Effects

Dose-related decreases in pup weight gain and survival were observed in rats exposed to an oral dose of 150 mg/kg of terfenadine (which led to fexofenadine exposures that were approximately 3 times the exposure at the maximum recommended human daily oral dose of 180 mg of fexofenadine hydrochloride based on comparison of AUCs).

8.3 Nursing Mothers

It is not known if fexofenadine is excreted in human milk. There are no adequate and well-controlled studies in women during lactation. Because many drugs are excreted in human milk, caution should be exercised when fexofenadine hydrochloride is administered to a nursing woman.

8.4 Pediatric Use

The recommended doses of fexofenadine hydrochloride in pediatric patients 6 months to 11 years of age are based on cross-study comparison of the pharmacokinetics of fexofenadine in adults and pediatric subjects and on the safety profile of fexofenadine hydrochloride in both adult and pediatric subjects at doses equal to or higher than the recommended doses. The safety and effectiveness of fexofenadine hydrochloride in pediatric patients under 6 months of age have not been established.

The safety of fexofenadine hydrochloride is based on the administration of fexofenadine hydrochloride tablets at a dose of 30 mg twice daily demonstrated in 438 pediatric subjects 6 years to 11 years of age in 2 placebo-controlled 2 week seasonal allergic rhinitis trials. The safety of fexofenadine hydrochloride at doses of 15 mg and 30 mg given once and twice a day has been demonstrated in 969 pediatric subjects (6 months to 5 years of age) with allergic rhinitis in 3 pharmacokinetic studies and 3 safety studies. The safety of fexofenadine hydrochloride for the treatment of chronic idiopathic urticaria in subjects 6 months to 11 years of age is based on cross-study comparison of the pharmacokinetics of fexofenadine hydrochloride in adult and pediatric subjects and on the safety profile of fexofenadine in both adult and pediatric subjects at doses equal to or higher than the recommended dose.

The effectiveness of fexofenadine hydrochloride for the treatment of seasonal allergic rhinitis in subjects 6 to 11 years of age was demonstrated in 1 trial (n = 411) in which fexofenadine hydrochloride tablets 30 mg twice daily significantly reduced total symptom scores compared to placebo, along with extrapolation of demonstrated efficacy in subjects aged 12 years and above, and the pharmacokinetic comparisons in adults and children. The effectiveness of fexofenadine hydrochloride 30 mg twice daily for the treatment of seasonal allergic rhinitis in patients 2 to 5 years of age is based on the pharmacokinetic comparisons in adult and pediatric subjects and an extrapolation of the demonstrated efficacy of fexofenadine hydrochloride in adult subjects with this condition and the likelihood that the disease course, pathophysiology, and the drug’s effect are substantially similar in pediatric patients to those in adult patients. The effectiveness of fexofenadine hydrochloride for the treatment of chronic idiopathic urticaria in patients 6 months to 11 years of age is based on the pharmacokinetic comparisons in adults and children and an extrapolation of the demonstrated efficacy of fexofenadine hydrochloride in adults with this condition and the likelihood that the disease course, pathophysiology and the drug’s effect are substantially similar in children to that of adult patients. Administration of a 15 mg dose of fexofenadine hydrochloride to pediatric subjects 6 months to less than 2 years of age and a 30 mg dose to pediatric subjects 2 to 11 years of age produced exposures comparable to those seen with a dose of 60 mg administered to adults.

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