Paroxetine Ups Risk of Birth Defects, FDA Says

American Society of Health-System Pharmacists
December 12, 2005

BETHESDA, MD: The Food and Drug Administration (FDA) announced Thursday that the use of paroxetine by a woman during the first trimester of pregnancy increases the risk of her fetus having a birth defect. This information came after GlaxoSmithKline, maker of the Paxil line of paroxetine products, announced that preliminary results from a study suggested an increased risk of birth defects from first-trimester exposure to the antidepressant.

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Safety of Paroxetine During Early Pregnancy Questioned

American Society of Health-System Pharmacists
September 28, 2005
By Cheryl A. Thompson

BETHESDA, MD: Preliminary results from a study of medical and pharmacy claims data suggest that a woman's use of paroxetine during the first three months of pregnancy may increase her baby's risk for birth defects, GlaxoSmithKline recently announced.

The new information is at odds with earlier reports indicating no increased risk of congenital malformations from early in utero exposure to paroxetine.

A "Dear Healthcare Professional" letter (PDF) circulated Tuesday by the Food and Drug Administration (FDA) stated that the risk of congenital malformations from first-trimester use of an antidepressant seemed greater with paroxetine than the other agents.

GlaxoSmithKline, which markets the paroxetine-containing products Paxil and Paxil CR, recommended that health care providers discuss the new information with patients who are or may be taking the antidepressant during pregnancy.

The study found that the odds of a birth defect developing in a fetus exposed to paroxetine during the first trimester were more than twice that of no defect occurring in a fetus exposed during the first trimester to an antidepressant other than paroxetine, the company reported. A similar odds ratio was found for the risk of cardiovascular malformations.

Overall, about 4 percent of the infants exposed to paroxetine in the first trimester had a congenital malformation. About 2 percent of the paroxetine-exposed infants had a cardiovascular malformation, usually a defect in the partition that separates the two ventricles.

A 1999 Teratology article cited by GlaxoSmithKline reported that the U.S. prevalence of birth defects was about 3 percent and the occurrence of cardiovascular malformations was about 1 percent.

The company said that the preliminary results of its "retrospective epidemiologic study" and other information recently reported by two research groups differ from what had been known before. For example, information from the Swedish Medical Birth Registry, founded in 1973, had not suggested an increased risk of major birth defects from the use of paroxetine or other selective serotonin-reuptake inhibitors.

The FDA-designated pregnancy category for paroxetine products remains C, meaning a lack of adequate, well-controlled studies of the drug's effect on the human fetus.

Details about the GlaxoSmithKline study (PDF)—a secondary analysis of databases containing insurance information from United HealthCare Services Inc., a national managed care organization—can be found at the drug company's clinical trial register.

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