The U.S. Food and Drug Administration (FDA) has given Fast Track designation to vigabatrin, an anticonvulsant marketed as Sabril, for evaluation as an anti-craving drug for cocaine and methamphetamine addiction. If approved, it would be the first medication ever approved for the treatment of addiction to stimulants.
The Fast Track designation at the FDA is intended to speed up the evaluation of drug treatments aimed at life-threatening disorders for which no current treatments exist. A 2006 study by the Substance Abuse and Mental Health Services Administration estimated that there were more than one million cocaine and methamphetamine addicts in the U.S.
First synthesized as a drug treatment for epilepsy in 1974, Sabril increases brain levels of the neurotransmitter GABA, an inhibitory compound also implicated in alcoholism. According to a press release from Ovation Pharmaceuticals, a marketer of the drug, “Sabril may block the euphoria associated with cocaine administration in humans and may suppress craving by increasing brain levels of gamma-aminobutyric acid (GABA).” Catalyst Pharmaceutical Partners has also announced plans to proceed with Sabril testing.
Ovation is collaborating with the NIDA on Phase II studies to evaluate the safety of Sabril, with Phase III trials scheduled for the end of this year. FDA has never approved the drug for use in the U.S., citing concerns over retinal damage in patients overseas.
Earlier animal testing and two limited early-stage studies on human addicts in 2003-2004 have convinced the company that Sabril diminishes cravings for stimulants. It may also blunt the euphoric effect of meth and cocaine. "This is unheard of in addiction treatment," Stephen Dewey of the Brookhaven National Laboratory, a member of an earlier vigabatrin study team, told New Scientist in 2003 . "There are no medicines that are effective at blocking cocaine craving in addicts."
Writing in the November 2004 issue of Synapse , Jonathan D. Brodie and colleagues at the New York University School of Medicine reported that “A rapid elevation in nucleus accumbens dopamine characterizes the neurochemical response to cocaine, methamphetamine, and other drugs of abuse. CITE Previously, we demonstrated that this response and associated behaviors are attenuated or even blocked by Vigabatrin, an antiepileptic drug and an irreversible inhibitor of GABA-transaminase."
However, the New Scientist also reported that many doctors who work with cocaine addicts were skeptical. "Cocaine is a recreational drug. The vast majority of people who take cocaine or crack want to continue doing so," said Allan Parry, a drug counselor in Liverpool, UK. "So in that sense this work is only likely to be relevant to a tiny minority of people. People often give up cocaine because their lifestyle changes or they just grow up."
Ovation said it was “pleased that the FDA has recognized the significant need for effective treatment options to address stimulant addiction, which is a major public health problem.”
Since there are no FDA-approved medications for cocaine or methamphetamine addiction, current treatment strategy centers on cognitive and behavioral approaches.