Diabetes drug could treat illicit drug addiction

By Piriya Mahendra, medwireNews Reporter

Researchers have found that a drug currently used to treat Type 2 diabetes could treat addiction to drugs such as cocaine.

Exendin-4 (Ex-4) is an analog of glucagon-like peptide (GLP-1) and, under its synthetic trade name of exenatide, is used to treat Type 2 diabetes. In a test of conditioned place preference, Gregg Stanwood (Vanderbilt University, Nashville, Tennessee, USA) and team found that the rewarding effects of cocaine were attenuated in mice injected with Ex-4.

Moreover, the effect of cocaine was attenuated regardless of the dose of Ex-4 given, suggesting that Ex-4 reduced the hedonic effects of cocaine, say the authors, who believe that their findings could have important implications for addicts.

"What we have demonstrated is that a brain mechanism already known to be therapeutic for the treatment of diabetes also appears to be implicated in at least certain types of drug addiction," remarked Stanwood in a press statement.

Co-author Aurelio Galli, also from Vanderbilt University, added: "I think the power of this research is that it is so easily translatable to humans because it is already [US Food and Drug Administration] approved.

"This is the first indication that it will work on psychostimulants. So our studies offer immediate translational opportunities to improve outcomes in human [drug] abusers."

The team found that Ex-4 treatment alone at any dose did not condition an aversion to, or a preference for, the treatment chamber during the test phase following cocaine treatment, as there was no significant change in the amount or proportion of time spent there. This "suggests that patient compliance owing to negative side effects or the potential for addiction to Ex-4, respectively, is of little concern," the authors write in Molecular Psychiatry.

Stanwood said that the extrapolation of the team's findings into the human population must be approached cautiously, but he believes that they have obtained promising data. He pointed out that addiction in humans is very complex and involves a host of genetic and environmental factors, so it is unlikely that all types of drug addiction would respond homogeneously to Ex-4 therapy.

"There are no medically based therapies for stimulant addiction that have been successful in the clinic although there are a variety of psychosocial and behavioral therapies that are somewhat effective in some people," he explained. "The beauty of this is that it targets a completely new mechanism so we are cautiously hopeful that the field will be able to exploit this, to provide a pharmacological way to help patients combat the disorder."

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