Opioid reinforcement in heroin-dependent volunteers during outpatient buprenorphine maintenance

FRANÇAIS :
Les effets de renforcement de l'hydromorphone (HYD) sont étudiés chez des volontaires substitués par la buprénorphine pendant deux semaines, à différentes doses (2,4,8mg). Huit volontaires sont abstinents d'héroïne et six continuent leur consommation. Chez les abstinents, l'HYD a peu d'effets de renforcement alors que chez les non-abstinents, l'effet de renforcement de l'HYD augmente avec la dose et n'est pas atténué par la buprénorphine. Cet essai clinique confirme les résultats de laboratoire, montrant que la buprénorphine n'atténue pas les effets de renforcement des opioïdes.
ENGLISH :
This study examined the reinforcing effects of hydromorphone (HYD) (0, 4, 8, and 16 mg/70 kg i.m.) in heroin-dependent outpatient volunteers maintained on buprenorphine (BUP) at doses of 2, 4, and 8 mg, each for 2 weeks. Following 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 minimal reinforcing value, whereas in nonabstainers there were marked dose-related increases in HYD reinforcing value, which were not attenuated by increasing doses of BUR A similar pattern was found for HYD subjective agonist effects. 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 differential effect. In summary, BUP effects on opioid reinforcement were consistent from outpatient setting (heroin abstinence) to laboratory setting (decreased HYD reinforcement), supporting the validity of this laboratory model. (Author' s abstract)