Topamax Cleft Palate Problems May Impact New Weight Loss Drug

It appears that concerns about the risk of birth defects from use of Topamax (topiramate) during pregnancy may impact a new proposed diet drug that combines the epilepsy medication with phentermine.

According to an analysis by Vivus Inc., the developer of the experimental weight loss drug named Qnexa, women who receive topiramate during the first trimester of pregnancy may be twice as likely to give birth to a child with a cleft lip or cleft palate, when compared to women who used the medication prior to becoming pregnant.

The potential risk of Topamax cleft palate and lip problems led the FDA to reject Qnexa in October 2010. The federal regulatory agency asked Vivus, Inc. to review reports of oral clefts with Topamax, which resulted in this analysis.

Vivus examined data from 15,000 medical claims involving Topamax and generic topiramate, which is prescribed for treatment of epilepsy and migrains. The analysis found that 0.36 percent of women who took topiramate during pregnancy gave birth to children with a cleft palate or cleft lip, compared to 0.16 percent among women who used Qnexa prior to becoming pregnant, but not during the pregnancy.

In March 2011, the FDA required new warnings about the risk of birth defects with Topamax and generic topiramate when the medication is used during the first trimester of pregnancy, a time when many women do not even know that they are pregnant.

The FDA urged doctors to avoid giving Topamax to pregnant women or women who are of child-bearing age and at a high risk of pregnancy, as the agency determined that alternative epilepsy and migraine medications were available that may not carry the same risk.

Cleft palate and cleft lip occur when parts of the lip or palate fail to completely fuse together. The defect results in the child being born with defects as small as a notched lip to extreme as an open groove that goes from the roof of the mouth to the nose. Cleft palate and cleft lip can cause problems eating and talking and can increase the risk of ear infections, resulting in the need for corrective surgery.

It is unclear whether this new data will prevent the FDA from approving Qnexa or lead to strong warnings and a risk mitigation strategy to make sure women avoid use of the diet drug during pregnancy. Vivus indicates that it is continuing to confirm the medical claims and does not expect the analysis to be complete until later this year.