Risk of Cleft Palate or Lip From Topamax Raises Concerns About New Diet Pill

A new weight loss drug being heralded because of its potential for long-term use, may carry a potential risk of severe birth defects when used early in pregnancy, such as a risk of cleft palate and cleft lip, because of it contains the same active pharmaceutical ingredient used in Topamax, an epilepsy drug. 

According to a study published in the latest issue of The Lancet medical journal, combining the short-term weight loss drug phentermine with topiramate, the active ingredient in Topamax, could be an effective long-term weight loss drug. However, the study’s findings were released just a month after the FDA warned about a potential risk of cleft lip and cleft palate from Topamax when the drug is used during pregnancy.

The study was a 56-week trial where 2,487 overweight patients were given either a combination of phentermine and Topamax in various dosages, or a placebo. Patients given low doses of the drugs lost an average of 18 pounds during the study, patients on high doses lost 22 pounds and those given a placebo lost three pounds.

Researchers say there were nine pregnancies during the study, but none resulted in a child being born with birth defects. Side effects that were observed included dry mouth, constipation, insomnia, and dizziness.

Earlier this year, as part of their review for the proposed new combination weight loss drug, which would be marketed as Qnexa, the FDA required the drug maker Vivus, Inc. to review potential reports of Topamax cleft palate and cleft lip among children born to women who took Topamax during pregnancy.

Topamax (topiramate) was first approved for treatment of epilepsy, which is a neurological disorder characterized by recurrent uncontrolled seizures. In 2004, the FDA approved Topamax for an additional use of treating severe headaches known as migraines. It is also used off-label by many doctors to treat bipolar disorder. Generic forms of the drug began to appear in 2006.

On March 4, the FDA announced that new warnings would be added to the medication’s label about the risk of oral clefts from Topamax when the medication is used during the first trimester of pregnancy, a time when many women do not even know 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 alternative drugs may not carry the same risk for the unborn child.

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.

A number of women who have given birth to children with a defect or malformation after using the drug while pregnant are considering a potential Topamax lawsuit against the drug makers as a result of their failure to research the pregnancy risks associated with the medication or adequately warn about the risk of Topamax cleft palate and lip problems.