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Recovery May Be Harder for Cocaine Addicts Who Smoke Pot

Oct. 5, 2001 -- It's hard for addicts to stay off drugs once they've quit. Now there's evidence that marijuana -- not itself an addictive drug -- may provoke relapse to cocaine addiction.

The news isn't all bad. The findings suggest that new medicines could have the opposite effect and make it easier for people to stay off drugs and alcohol. An animal study reported in the current issue of Nature Medicine shows that one such compound -- dubbed SR14176A -- has exactly this effect.

"The 'anti-relapse' effect of SR14176A provides a rationale for the use of [similar compounds] for the prevention of relapse in abstinent drug addicts," suggest study authors Taco J. De Vries and co-workers from Vrije University in Amsterdam.

"An agent that 'takes the edge off' craving would provide an invaluable complement to behavioral therapy and psychotherapy," agrees Daniele Piomelli, PhD, of the University of California, Irvine, in an editorial accompanying the study.

The main ingredient of marijuana is THC, which mimics a natural substance in the body that plugs into specialized outlets on brain cells. These outlets -- called cannabinoid receptors -- are part of an elaborate system that helps control a number of important brain functions. Researchers have found two different types of chemicals that affect this system. One of these compounds, dubbed HU210, "turns on" the cannabinoid system as THC -- but much more powerfully. SR14176A is the other type of compound, which blocks the switch to the cannabinoid system.

The Dutch researchers found that these compounds did not speed or slow the addiction process. But once addicted animals were weaned from cocaine, they were much more likely to engage in drug-seeking behavior if they got HU210. On the other hand, they were much less likely to seek cocaine if they got a dose of SR14176A.

De Vries tells WebMD that the marijuana-like drug used in his study, HU210, is much stronger than marijuana. "Compared to other drugs of abuse, marijuana is a relatively mild activator of this system. [Even] HU210 in our study is much weaker than re-exposure to cocaine itself. But there is a potential risk. There are many cocaine addicts that use marijuana and so far it has not been studied to what extent this may contribute to the persistence of drug seeking behavior."

"One would expect [marijuana] to precipitate relapse, though to a minor extent compared to the extremely potent compound used by the De Vries group," Piomelli tells WebMD.