Weight-loss drug may have long-term risks, FDA says

WASHINGTON — Federal health officials continue to voice safety concerns over an experimental diet pill from drugmaker Vivus Inc., which will make its second attempt to convince experts of the drugs' safety next week. The drug Qnexa helped people lose weight but may cause long-term health problems in overweight and obese patients, Food and Drug Administration reviewers said.

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The FDA staff will ask an advisory panel to consider whether the drug's benefits for obese patients will outweigh its risk of birth defects and heart problems.

In documents posted online on Friday, FDA reviewers said patients taking Qnexa during a clinical trial lost more weight, and kept it off for longer, than patients taking a placebo, or sugar pill. These patients also had lower levels of problems associated with obesity, such as issues with blood pressure and blood sugar.

However, patients taking the drug had more safety problems than patients on a placebo, including memory loss and birth defects, and these problems could get worse over time.

Qnexa is a combination of appetite suppressant phentermine and anti-seizure drug topiramate.

A company study in December showed topiramate caused a higher rate of oral clefts in infants of women taking the drug during pregnancy, and the company said it would limit Qnexa to women who are not pregnant.

The FDA already rejected Qnexa in 2010 because of safety concerns -- including elevated heart rate in some users and the potential for birth defects if pregnant women used the drug.

Vivus resubmitted its application in October, proposing to limit the drug to only women who cannot have children. In January, the company broadened the label to just limit pregnant women from taking the drug, in response to an FDA request.

An advisory panel of outside experts will vote Feb. 22 on whether to recommend the drug. The group's recommendation is not binding, and the FDA is expected to make its final decision by April 17.