Published: Jul 17, 2012 7:21 PM EDT
Updated: Jul 18, 2012 6:30 AM EDT

WASHINGTON (AP) - The U.S. Food and Drug Administration is approving a weight loss drug from Vivus Inc. that many doctors consider the most effective therapy among a new generation of anti-obesity pills.

The agency cleared the pill Qsymia for adults who are obese or overweight and have at least one weight-related condition such as high blood pressure, diabetes or high cholesterol.

Patients taking Qsymia for one year lost 11 percent of their body weight, on average. That was more than two other weight loss pills recently reviewed by the FDA.

Qsymia is the second weight loss drug approved by the FDA in less than a month. In late June the agency approved Arena Pharmaceutical's pill Belviq. Previously the agency had not approved a new drug for long-term weight loss since 1999.