Evaluation of the reinforcing and subjective effects of heroin in combination with dextromethorphan and quinidine

Abstract

Studies have suggested that the N-methyl-D-aspartate antagonist dextromethorphan may be useful in the treatment of opioid dependence. This double-blinded, placebo-controlled inpatient study evaluated the effects of 0, 30, and 60 mg of dextromethorphan and quinidine (DMQ) on the reinforcing and subjective effects of heroin in recently detoxified heroin abusers. Nine heroin-dependent participants were admitted and then detoxified from heroin over the course of several days. Participants were subsequently stabilized on 0, 30, or 60 mg of DMQ. Each dose of DMQ was administered for two consecutive weeks, and the effects of heroin (0, 12.5, and 50 mg) were studied under each DMQ maintenance dose condition. DMQ and heroin dose were administered in random order both within and between participants. Planned comparisons revealed statistically significant increases in progressive ratio breakpoint values and positive subjective ratings as a function of heroin dose. There were no consistent changes in any of the responses as a function of DMQ maintenance dose, other than a modest reduction in craving. In summary, results from this study suggest that maintenance on dextromethorphan in combination with quinidine has a limited role in the treatment of opioid dependence.