Glaxo Says It Does Not Know Whether Paxil Causes Any Abnormality or Malformation in Babies

A September 27, 2005 FDA MedWatch alert broadcast the news that GlaxoSmithKline Plc had sent a "Dear Doctor" letter to physicians concerning a recent retrospective study suggesting Paxil may be linked more often to birth defects than some other antidepressants.

In the September 2005 Paxil Dear Doctor letter, Glaxo concluded that it was difficult to tell if Paxil caused the birth defects because of the "differences in the results from the available studies and the diversity in the type of abnormalities…."  The drug maker, nonetheless, thought it "important" that information derived from the new retrospective epidemiological study be made available to doctors for their consideration.

The Paxil Dear Doctor letter starts by pointing out that the current Paxil package insert, or "label", stated that there are no adequate studies in humans to determine the effect of Paxil, if any, on a fetus, i.e., Category C pregnancy precaution.  In the recently completed retrospective study, investigators examined the records of infants born to 3,581 women who took Paxil or other antidepressants during the first trimester of pregnancy and looked for major congenital malformations.  A preliminary analysis of the investigators’ findings indicated that infants born to women who took Paxil were more likely to be born with an abnormality or malformation — most of which were cardiovascular — than babies born to women who took another antidepressant.

Based on these findings from this new study, the September 2005 Paxil Dear Doctor letter from Glaxo included these points:

• Preliminary results suggest an increase in the risk of congenital malformations associated with the use of Paxil as compared to other antidepressants;
• The preliminary results of this study and recent abstracts differ from previous epidemiologic studies, making it difficult to conclude whether a causal relationship exists; and,
• Physicians should carefully weigh the potential risks and benefits of using Paxil therapy in women during pregnancy and discuss these findings as well as treatment alternatives with their patients.

The complete FDA MedWatch Paxil alert, including links to the Dear Healthcare Professional ("Dear Doctor") Letter and the revised Paxil labeling, can be found on the FDA’s web site.

Significantly, Glaxo said it will be conducting additional epidemiological studies in order to determine whether there is an increased risk of birth defects among pregnant women using Paxil.

(Posted by: Tom Lamb)