Paxil

Antidepressant Drug Paxil Linked to Birth Defects

An increased risk of severe birth defects, including septal heart defects and other congenital abnormalities, is associated with use of the anti-depressant drug Paxil (paroxetine) by pregnant women, particularly during the first trimester of pregnancy.

Approved by the FDA in 1992, Paxil is a commonly prescribed medication used to treat depression and other mood disorders including social anxiety disorder, obsessive compulsive disorder (OCD), panic disorder (PD), generalized anxiety disorder (GAD), and posttraumatic stress disorder (PTSD). In 2006 the American Medical Association (AMA) estimated that over one percent (40,000) of pregnant women in the U.S. were taking antidepressants. GlaxoSmithKline, the maker of Paxil, also stated that in that year about 25 percent of prescriptions for Paxil (including generics) were written for women of childbearing age. The drug generated about $942 million in sales for GSK in 2008 alone.

Paxil belongs to a class of drugs known as Selective Serotonin Reuptake Inhibitors (SSRIs).  SSRIs are designed to relieve the symptoms of depression by blocking the reabsorption (reuptake) of the "feel good" chemical serotonin by certain nerve cells in the brain. With more serotonin available in the brain, mood is improved. SSRI's are called "selective" because they generally affect only serotonin, and not other brain chemicals. However, maternal serotonin plays a crucial role in fetal heart, lung and brain development. Because Paxil is known to cross the placenta, the risk of cardiovascular and other congenital malformations may be increased in babies born to mothers who took Paxil during pregnancy.

Paxil and the FDA

In December 2005 the U.S. Food and Drug Administration (FDA) issued a public health advisory warning of the increased risk of birth defects, particularly heart malformations, with Paxil use in pregnancy.

The early results of two studies 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 as women who received other antidepressants or women in the general population. One study showed the risk of heart defects in babies whose mothers had taken Paxil early in pregnancy was about 2 percent, compared to a 1 percent risk in the whole population. In the other study, the risk of heart defects in babies whose mothers had taken Paxil in the first trimester was 1.5 percent, compared to 1 percent in babies whose mothers had taken other antidepressants in the first three months of pregnancy.

Most of the heart defects reported in these studies were atrial and ventricular septal heart defects (holes in the walls of the chambers of the heart), ranging in severity from minor defects to those requiring surgery to repair. The FDA advised doctors 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.

Birth Defects Associated with Paxil Use in Pregnancy

Paxil poses a particular risk for pregnant women.  It is the only SSRI on the market that is classified by the FDA as a Category D drug.  Category D means that studies in pregnant women have demonstrated a risk to the fetus.  Paxil birth defects may include:

• congenital heart defects such as atrial and ventricular septal defects, hypoplastic left heart syndrome, tricuspid atresia, and pulmonary stenosis

• Other birth defects such as neural-tube defects, craniosynostosis, infant omphalocele, congenital foot deformity (ie. club foot), anal atresia, and certain lung defects (ie. PPHN)

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