Fexofenadine in Pregnancy and Breastfeeding
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Fexofenadine (Allegra )
Anihistamine. Active metabolite of terfenadine.
Molecular weight: 538.13. Fexofenadine hydrochloride is 60% to 70% bound to plasma proteins.

"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 31 times, respectively, the exposure from the maximum recommended daily oral dose of fexofenadine in adults)."[1].

Dose-related decreases in pup weight gain and survival were observed in rats exposed to an oral dose of 150 mg/kg of terfenadine (approximately 3 times the maximum recommended daily oral dose of  fexofenadine hydrochloride in adults based on comparison of fexofenadine hydrochloride AUCs) [1].

Because terfenadine is rapidly and nearly completely biotransformed  to its active metabolite fexofenadine [2] studies addressing the safety of terfenadine during pregnancy may be relevant in assessing the safety of fexofenadine during human gestation.

The American College of Obstetricians and Gynecologists (ACOG) and The American College of Allergy, Asthma and Immunology (ACAAI) have recommended chlorpheniramine and tripelennamine as the antihistamines of choice for pregnant women.  Cetirizine and loratadine may be considered (preferably after the first trimester) in patients who cannot tolerate or do not respond to maximal doses of chlorpheniramine or tripelennamine [3]

BREAST FEEDING: Fexofenadine appears to be excreted into breast milk. In a study of  four healthy lactating mothers subjects received 60 mg terfenadine every 12 hours over a period of 48 hours. Terfenadine was not detected in milk or plasma. However, fexofenadine was found in milk and plasma.

The AUCmilk/AUCplasma (0-12) ratio for fexofenadine was 0.21 (range 0.12 to 0.28)

Newborn dosage estimates based on the highest measured concentration of fexofenadine in milk suggest the maximum level of newborn exposure would not exceed 0.45% of the recommended maternal weight-corrected dose  [4].


1. Physicians Desk Reference 57th ed. Montvale, NJ: Thomson PDR; 2004: 713-714
2.Honig PK, et al. The effect of fluconazole on the steady-state pharmacokinetics and electrocardiographic pharmacodynamics of terfenadine in humans.Clin Pharmacol Ther. 1993 Jun;53(6):630-6. MEDLINE
3. The use of newer asthma and allergy medications during pregnancy. Position Statement. The American College of Obstetricians and Gynecologists (ACOG) and The American College of Allergy, Asthma and Immunology (ACAAI). Ann Allergy Asthma Immunol. 2000;84:475-480. MEDLINE
4. Lucas BD, et al. Terfenadine pharmacokinetics in breast milk in lactating women.Clin Pharmacol Ther. 1995 Apr;57(4):398-402. MEDLINE

Created: 11/17/2000
Updated: 11/30/2002
Updated: 4/17/2004

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