After first being turned down by the Food and Drug Administration, makers of the investigational weight-loss drug Qnexa have promising new data to report and will ask less of the FDA this time around.

Vivus Inc, of Mountain View, Calif., sought FDA approval last year to market Qnexa for weight loss in adults. But the request was denied with the FDA citing a potential side effect in women who become pregnant while taking the medication. Qnexa is a combination of two existing drugs — the stimulant phentermine and the anti-seizure drug topiramate. Topiramate, however, has been linked to cleft palates.

Now Vivus is asking for approval of Qnexa with labeling that would exclude use by women of child-bearing age. If approved, Qnexa would join Xenical as the only other prescription weight-loss medication. Several other companies seeking approval of new weight-loss drugs have also hit a brick wall with FDA in recent years.

The new filing on Qnexa before the FDA shows an average weight loss of 14 percent over one year. However, another study, published online this week in the American Journal of Clinical Nutrition, is a summary of weight loss over two years of use and finds an average loss of about 10 percent of initial body weight. Patients also had improved cardiovascular and metabolic risk factors, such as lower cholesterol and a lower risk of diabetes.

The FDA is expected to reach its decision on Qnexa in the first half of 2012.