Empatic, a diet drug that combines two FDA-approved drugs, zonisamide SR and bupropion SR, produced significant weight loss in a 24-week Phase IIb trial, according to its developer Orexigen Therapeutics, Inc.

The randomized, double-blind, placebo-controlled trial, conducted with the Company's novel formulation of zonisamide paired with bupropion SR, at the highest dose tested produced an 8.6% weight loss in patients compared to 1.1% for a placebo.

"In addition, the trajectory of weight loss for all treatment arms appeared to continue downward through 24 weeks," Orexigen said.

"These trial results illustrate that we can delay the early weight loss plateau often seen with dieting and many existing pharmaceutical approaches and also improve tolerability with a sustained release formulation of zonisamide," said Orexigen President and Chief Executive Officer, Dr. Gary Tollefson.

"If the magnitude of weight loss evident in this trial continues to be seen, we believe that Empatic may be particularly useful in severely obese individuals," Tollefson said.

Bupropion and zonisamide each target reciprocal pathways in the hypothalamus that separately mediate appetite and energy expenditure, according to Orexigen.

Bupropion, one of the most commonly prescribed antidepressants in the U.S. , was approved for marketing in the United States in 1985 for depression and in 1997 for smoking cessation.

Zonisamide, in an immediate release formulation, was approved in the United States in 2000 for the adjunctive treatment of partial seizures, which is a form of epilepsy.

"The unique combination of these molecules is designed to provide more clinically meaningful weight loss for patients by both initiating weight loss and sustaining it over a longer period of time," an Orexigen spokesperson said.