Weight Loss From Addiction Drug

Aug. 20, 2008 -- A drug being tested as a treatment for drug addiction makes obese lab rats lose weight.

The drug is vigabatrin. It was originally developed as an epilepsy treatment. A version of vigabatrin is sold as Sabril in Canada, but because the drug can damage the retina -- leading to vision problems -- it's not approved in the U.S.

Researchers Stephen Dewey, PhD, Amy DeMarco, and colleagues at Brookhaven National Laboratory are exploring another version of vigabatrin under development by Catalyst Pharmaceutical Partners. A human trial is testing the drug as a possible treatment for long-term cocaine addiction.

Animal studies suggest that the same brain circuits responsible for addiction play a role in obesity. So Dewey's team tested vigabatrin in a strain of lab rats bred to be obese.

The result: The genetically obese rats lost up to 19% of their body weight. Non-obese rats lost 12% to 20% of their body weight.

"Our results appear to demonstrate that vigabatrin induced satiety in these animals," DeMarco says in a news release.

Vigabatrin prevents the breakdown of an important brain-messenger chemical called GABA, causing GABA levels to rise throughout the brain. This has a powerful effect in reducing drug craving. It also appears to make animals crave food less.

"That these results occurred even in genetically obese rats offers hope that this drug could potentially treat severe obesity -- even if it results from binge eating, a disorder characterized by a pattern of food consumption similar to the pattern of cocaine abuse observed in dependent subjects," DeMarco and colleagues suggest.

A report on the study appears in the Aug. 20 online issue of the journal Synapse.

Ovation Pharmaceuticals holds the U.S. rights to develop vigabatrin as an epilepsy treatment. The company is also interested in the drug's potential as treatment for addiction. Vigabatrin was originally made by Sanofi-Aventis.