GSK: PAXIL MAY CAUSE INCREASED RISK OF BIRTH DEFECTS
A new epidemiologic study of GlaxoSmithKline's (GSK) top-selling antidepressant Paxil suggests the drug may be associated with an increased risk of birth defects compared to other antidepressants, GSK states in a recently issued "Dear Healthcare Professional" letter.
GSK's letter, which was recently posted to the FDA's website, warns that pregnant women exposed to Paxil (paroxetine HCl) or Paxil CR (paroxetine HCl controlled-release tablets) during the first trimester were more than twice as likely to have a child with birth defects than women taking other antidepressants. The warning was based on preliminary data from a GSK-led retrospective epidemiologic study involving nearly 3,600 pregnant women, according to the letter.
The preliminary analysis suggests the most common types of birth defects in the Paxil group were cardiovascular malformations, namely ventricular septal defects. According to GSK's early data, pregnant women taking Paxil had a 2.2 times greater chance of having a child with any type of birth defect, and a 2.1 times greater chance of having a child with a cardiovascular-related birth defect, compared to women taking other antidepressants.
GSK notes in its letter that the study results differ from previous epidemiologic studies, "making it difficult to conclude whether a causal relationship exists" between Paxil use and birth defects. For example, data from the Swedish Medical Birth Registry, one of the largest available birth registries, have not shown there is an increased risk of major malformations when taking selective serotonin reuptake inhibitors, including paroxetine.
To inform doctors about the potential health risk, GSK has revised the "Pregnancy/Precautions" section of the labeling for Paxil and Paxil CR to describe the results of epidemiologic study. The FDA-approved labeling for Paxil products already carries a "Category C" pregnancy warning, indicating that there are no adequate and well-controlled studies in humans to determine the effect of paroxetine on the fetus. The labeling also states that the drug should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
To view GSK's letter, go to http://www.fda.gov/medwatch/safety/2005/Paxil_dearhcp_ letter.pdf (http://www.fda.gov/medwatch/safety/2005/Paxil_dearhcp_letter.pdf).