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Psychopharmacology (Berl). 2005 Sep;181(2):237-43. Epub 2005 Apr 14.

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

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  • 1Division on Substance Abuse, New York State Psychiatric Institute and Department of Psychiatry, College of Physicians, Surgeons of Columbia University, NY 10032, USA.



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.


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


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.


Participants chose active Delta(9)-THC (10 and 20 mg) more often than placebo (<two selections vs approximately four selections, respectively). However, they chose active Delta(9)-THC on less than 50% of choice opportunities. Both active Delta(9)-THC doses produced significant increases in "positive" subjective effects, impaired psychomotor performance, and increased heart rate, relative to the placebo conditions.


These data indicate that oral Delta(9)-THC may have modest abuse liability in experienced marijuana smokers.

[PubMed - indexed for MEDLINE]
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