Opioid reinforcement in heroin-dependent volunteers during outpatient buprenorphine maintenance

This study examined the reinforcing effects of hydromorphone (HYD) (0, 4, 8 , and 16 mg/70 kg i.m.) in heroin-dependent outpatient volunteers maintaine d on buprenorphine (BUP) at doses of 2, 4, and 8 mg, each for 2 weeks. Foll owing a week of maintenance at each dose, volunteers received injections of one of the four HYD doses under double-blind conditions. Eight volunteers (abstainers) were heroin-free during HYD test weeks, whereas six volunteers remained heroin-positive (nonabstainers). Among abstainers, HYD had minima l reinforcing value, whereas in nonabstainers there were marked dose-relate d increases in HYD reinforcing value, which were not attenuated by increasi ng doses of BUP. A similar pattern was found for HYD subjective agonist eff ects. Heroin craving among nonabstainers was significantly higher compared with abstainers, and was reduced in a dose-related manner by HYD. Although BUP and HYD produced dose-related miosis, abstinence status had no differen tial effect. In summary, BUP effects on opioid reinforcement were consisten t from outpatient setting (heroin abstinence) to laboratory setting (decrea sed HYD reinforcement), supporting the validity of this laboratory model. ( C) 1999 Elsevier Science Ireland Ltd. All rights reserved.