Heroin craving and drug use in opioid-maintained volunteers: effects of methadone dose variations.

Recent data indicate that opioid agonist and antagonist challenges decrease and increase (respectively) heroin craving in physically dependent individuals. This study investigated effects of methadone dose variations on craving and new drug use in 18 outpatients who were given money contingencies. In Phase 1, volunteers were told in different test sessions that methadone dose would increase, decrease, or stay the same; drug-abstinence contingencies were suspended for 24 hr. Craving significantly increased and new heroin use marginally increased (relative to maintenance dose) only when a dose reduction was paired with a dose decrease instruction. In Phase 2 (detoxification), craving and heroin use significantly increased as methadone dose decreased. Thus, loss of micro-receptor agonist effect increased craving and risk of relapse.