Reinforcing effects of oral Delta9-THC in male marijuana smokers in a laboratory choice procedure.

Rationale: Oral Delta-9-tetrahydrocannabinol (Delta(9)-THC; Marinol) is medically available for the treatment of nausea associated with cancer chemotherapy and for wasting syndromes related to HIV/AIDS. Little is known about its reinforcing effects.

Objective: This study was conducted to characterize the reinforcing effects of oral Delta(9)-THC in experienced marijuana smokers under controlled laboratory conditions.

Methods: Ten healthy male marijuana users completed this 17-day residential study. On days 2, 6, 10, and 14, at 0900 h, participants received a "sample" oral dose of Delta(9)-THC (0, 10, 20 mg) and an alternative reinforcer, a 2 US dollars voucher (redeemable for cash at study's end). Over the next 3 days, they had 11 opportunities to self-administer either the sampled dose of Delta(9)-THC or to receive a 2 US dollars voucher.

Results: Participants chose active Delta(9)-THC (10 and 20 mg) more often than placebo (
Conclusion: These data indicate that oral Delta(9)-THC may have modest abuse liability in experienced marijuana smokers.