Craving and drug reward: a comparison of methadone and clonidine in detoxifying opiate addicts.

Based upon findings relating to the reinstatement of responding from the animal laboratory, the present study investigated whether methadone, a synthetic opiate, would prime the desire to use heroin for its pleasant effect (i.e. for positive reinforcement) compared to clonidine, a non-opiate drug, in detoxifying opiate addicts (n = 16). In-patient opiate addicts were tested at maximum withdrawal and minimal withdrawal, and self-reported desire to use heroin (i) for its pleasant effect (positive craving) and (ii) to alleviate an unpleasant feeling or mood (negative craving) was recorded before drug administration, immediately after drug administration and on 4 further occasions, 15 min apart. In addition, self-reported rating of opiate withdrawal symptoms were also recorded. Although elevated in the methadone group, the difference between methadone and clonidine groups in positive craving did not reach statistical significance. Interpretation of the data is complicated by elevated baselines of positive craving in the methadone group at minimum withdrawal. Measures of negative craving and self-reported withdrawal symptoms showed a similar pattern of decline, and were significantly correlated at maximum withdrawal, thereby providing evidence from substance misusers themselves that the constructs of positive and negative reinforcement can be differentiated.