Updated Product Labeling Warns of Birth Defect Risk with Paxil

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Medical Author: Melissa Conrad Stoppler, MD
Medical Editor: Dennis Lee, MD

The U.S. Food and Drug Administration (FDA) recently announced that early research studies with the drug Paxil (paroxetine) suggest that taking the drug during the first three months of pregnancy may increase a woman's risk of having a baby with birth defects, particularly heart defects.

Paxil is an antidepressant drug belonging to the class of medications known as the selective serotonin reuptake inhibitors (SSRIs). Drugs in this group affect levels of the chemicals that nerves in the brain use to communicate with one another, known as neurotransmitters. Many experts believe that an imbalance among the amounts of the different neurotransmitters in the brain leads to depression. The SSRI class also contains fluoxetine (Prozac) and sertraline (Zoloft). Paxil is approved by the FDA for the treatment of depression and several other psychiatric disorders.

Results of two early studies reviewed by the FDA showed that women who took Paxil during the first three months of pregnancy were about one and a half to two times as likely to have a baby with a heart defect compared with women who took other antidepressants or women in the general population. Most of the heart defects reported in these studies were of the type known as atrial and ventricular septal defects (holes in the walls of the chambers of the heart). These types of heart defects can range in severity from relatively minor that resolve without treatment to those that cause serious symptoms and need to be repaired surgically. The risk for this type of heart defect is approximately one per cent of births in the general population. In one of the studies with Paxil, women taking the drug had an approximately two per cent risk of having a baby with heart defects, and in the second study, women taking Paxil in the first trimester had an approximate 1.5% risk of having a baby with heart defects.

According to the FDA announcement:

FDA is advising health care professionals to discuss the potential risk of birth defects with patients taking Paxil who plan to become pregnant or are in their first three months of pregnancy. Health care professionals should consider discontinuing Paxil (and switching to another antidepressant if indicated) in these patients. In some patients, the benefits of continuing Paxil may be greater than the potential risk to the fetus. FDA is advising health care professionals not to prescribe Paxil in women who are in the first three months of pregnancy or are planning pregnancy, unless other treatment options are not appropriate.

The manufacturer of Paxil, Glaxo Smith Kline, has changed the product labeling from pregnancy class C to class D, meaning that that studies in pregnant women (controlled or observational) have demonstrated a risk to the fetus. However, the benefits of therapy with Paxil may outweigh the potential risks to the fetus.

It's important to note that these conclusions are preliminary and are based on early results of two studies. The FDA is collecting additional data and waiting for the final results of these and other studies in order to better characterize and understand the risk for birth defects associated with Paxil. If you're currently taking Paxil, talk to your doctor if you are pregnant or planning to become pregnant. He or she can advise you on the best course of action for your situation and medical condition.

Reference: FDA release P05-97 December 8, 2005Zq