Weight-loss drug show strong results as FDA set to rule

By Reuters
Posted Sep. 21, 2010 at 6:03 a.m.

An experimental weight-loss drug made by Vivus Inc. helped obese people lose more than 10 percent of their weight after two years in a clinical trial, but safety details were scant for the drug, which in July was turned down by a panel of U.S. experts.

The company said Tuesday that the second year of a clinical trial found that patients taking the highest dose of its drug, Qnexa, lost an average of 26 pounds, or 11.4 percent of their body weight. Patients taking a placebo had weight loss of 2.5 percent.

The results were slightly better than the previously reported one-year weight loss of 10.4 percent.

“The key thing is we were able to maintain more than 10 percent weight loss,” said Dr. Michelle Look, a San Diego family doctor and a trial investigator. “We currently don’t have any approved medication that is getting the results that Qnexa has shown.”

Advisers to the Food and Drug Administration voted not to recommend approval of the drug, citing concern the once-a-day capsule could cause depression, memory loss and potential birth defects if used among millions of overweight or obese Americans.

Vivus officials declined to comment on the latest trial results, citing the sensitivity of discussions with the FDA.

Look said no birth defects have been seen during trials of Qnexa. “Just like any other medications … we need to weigh risk and benefit,” she said.

All of the 675 obese or overweight patients in the two-year trial had two or more weight-related conditions such as diabetes or high blood pressure and the drug improved those conditions, Vivus said. Use of high-dose Qnexa reduced the incidence of a diabetes diagnosis during the trial by 76 percent compared with use of a placebo.

Vivus said the most common side effects seen with Qnexa were constipation, tingling, dry mouth, altered taste and insomnia. Serious side effects occurred in 4.1 percent of top-dose patients, 2.6 percent of mid-dose patients and 4 percent of the placebo group, but none of them were drug-related, according to the company.

About 17 percent of Qnexa patients and 14 percent of placebo patients dropped out of the trial. Some 4 percent of the drop-outs were because of adverse events in the Qnexa groups, compared with 2.6 percent for the placebo group.

Qnexa combines relatively low doses of the generic stimulant phentermine and epilepsy drug topiramate, which is sold under the brand name Topamax. It is a capsule designed to release the components in a way timed to minimize side effects.

Patients who took a lower dose of Qnexa lost 23 pounds, or 10.4 percent of their body weight.

Mountain View, Calif.-based Vivus said the two-year data, like the earlier one-year results, showed no evidence of suicidal thoughts or reports of suicide attempts.

The company also said the incidence of “targeted medical events” for sleep disorders, depression, anxiety, cardiac disorders and cognitive disorders was lower than seen during the one-year study.

Vivus said the effects of Qnexa on heart rate were “small” and seen in conjunction with improvements in blood pressure.

It said that for the more than 4,000 patients who have participated in trials of the drug, serious rates of cardiovascular and neurovascular side effects have been balanced between patients on the drug and those on a placebo.

The FDA is scheduled to make a decision on the Qnexa marketing application by Oct. 28.

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