Clemastine / phenylpropanolamine Pregnancy and Breastfeeding Warnings
Clemastine / phenylpropanolamine Pregnancy Warnings
Among Michigan Medicaid recipients, 1617 exposures to clemastine were reported the first trimester. Birth defects were observed in 71 infants (68 expected) and included 13 cardiovascular defects, 3 oral clefts, 3 spina bifida, 4 polydactyly, 4 hypospadias, and 5 limb reductions. No evidence was found to suggest a relationship to large categories of malformations, expect possibly limb reductions. (F. Rosa, personal communications, FDA, 1994) A review of prenatal drug use in 3026 women with premature infants demonstrated an increased risk of retrolental fibroplasia with antihistamine use during the last two weeks of pregnancy. The dosage used or the particular antihistamine was not specified. The incidence of retrolental fibroplasia in premature infants exposed in utero to antihistamine during this time was 21% compared to 11% in premature infants not exposed. In a review of deliveries to Michigan Medicaid patients during 1980 to 1983, 1489 exposures to phenylpropanolamine anytime during pregnancy were recorded. A total of 128 birth defects were reported (91 expected). An association was seen between phenylpropanolamine and laryngotracheal anomalies, pyloric stenosis, intestinal fixation anomalies, upper limb defects, skull/face anomalies, and musculoskeletal defects. The statistical significance of these associations is not known. (written communication, Franz Rosa, MD, Food and Drug Administration, 1994) The Collaborative Perinatal Project monitored 50,282 mother-child pairs and recorded 726 first-trimester exposures and 2489 exposures to phenylpropanolamine anytime during pregnancy. Possible associations between phenylpropanolamine and first trimester use include hypospadias (4), eye and ear (7, statistically significant), polydactyly (6), cataract (3), and pectus excavatum (7). For use anytime during pregnancy a possible association was noted between phenylpropanolamine use and congenital dislocation of hip (12).
Clemastine has been assigned to pregnancy category B by the FDA and phenylpropanolamine has not been formally assigned to a pregnancy category. There are no controlled data in human pregnancy for either of these agents. Clemastine-phenylpropanolamine is only recommended for use during pregnancy when benefit outweighs risk.
Clemastine / phenylpropanolamine Breastfeeding Warnings
Clemastine is excreted into breast milk. One breast-fed infant developed drowsiness, irritability, refusal to feed, neck stiffness, and a high-pitched cry 12 hours after her mother began clemastine therapy, 1 mg twice daily. The mother was also receiving carbamazepine and phenytoin. The infant returned to normal after clemastine was discontinued. Twenty hours after a dose of clemastine, the mother's serum and breast milk concentrations were 20 mcg/mL and 5 to 10 mcg/mL, respectively. The American Academy of Pediatrics recommends that clemastine be used with caution during breast-feeding. There are no data on the excretion of phenylpropanolamine into human milk. The manufacturer recommends that due to the potential adverse reactions in nursing infants, a decision should be made to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
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