Paxil: Stronger Birth Defects Warning
Heart-Related Birth Defects Noted in 2 Studies; Cause Not Clear
Dec. 8, 2005 -- The FDA and drug company GlaxoSmithKline have strengthened their warning about using the antidepressant drug Paxil during early pregnancy.
The warning is based on early results from two studies. The studies showed a higher rate of heart-related birth defects in babies born to women who took Paxil during early pregnancy than in babies of women in the general population or women who took other antidepressants.
The first of those studies prompted an
by GlaxoSmithKline, which makes Paxil, in September.
Now, results of the second study have prompted an update. The update includes moving Paxil to a category "D" medication instead of a category "C" for use during pregnancy.
That change reflects a stronger warning about use during early pregnancy. Category "D" drugs have shown risks to fetuses in studies of pregnant women. However in this category, the benefits of the therapy may outweigh the risks.
GlaxoSmithKline, a WebMD sponsor, is sending a letter to doctors with the updated information.
More Heart-Related Birth Defects
In both studies, heart-related birth defects were rare but more common among women who took Paxil in early pregnancy.
"The expectation is that in the general population, the risk of cardiovascular defects is about one per 100 infants," GlaxoSmithKline spokeswoman Gaile Renegar tells WebMD.
She says the studies show a risk of those heart-related birth defects is one per 50 babies born to women who used Paxil in early pregnancy.
Cause Not Clear
The studies didn't assign anyone to take Paxil and don't necessarily prove that Paxil caused those birth defects.
"It's not clear whether there's a true causal association," Renegar says.
Most of the heart defects reported in these studies were holes in the walls of the chambers of the heart (atrial and ventricular septal defects).
"In general," states the FDA, "these types of defects range in severity from those that are minor and may resolve without treatment to those that cause serious symptoms and may need to be repaired surgically."
According to the FDA, early results from the two studies showed that women who took Paxil during the first three months of pregnancy were about 1.5 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.
In one study, the risk of heart defects in babies whose mothers had taken Paxil early in pregnancy was about 2%, compared with a 1% risk in the whole population.
In the other study, the risk of heart defects in babies whose mothers had taken Paxil in the first three months of pregnancy was 1.5%, compared with 1% in babies whose mothers had taken other antidepressants in the first three months of pregnancy.