Reinforcing effects of oral Δ9-THC in male marijuana smokers in a laboratory choice procedure
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Oral Delta-9-tetrahydrocannabinol (Δ9-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 Δ9-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 Δ9-THC (0, 10, 20 mg) and an alternative reinforcer, a $2 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 Δ9-THC or to receive a $2 voucher.
Participants chose active Δ9-THC (10 and 20 mg) more often than placebo (<two selections vs ∼four selections, respectively). However, they chose active Δ9-THC on less than 50% of choice opportunities. Both active Δ9-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 Δ9-THC may have modest abuse liability in experienced marijuana smokers.
KeywordsCannabis Marinol Human Delta-9-tetrahydrocannabinol Self-administration Choice Subjective effects Performance
The National Institute on Drug Abuse provided financial support for this research (Grant #DA-03746). We gratefully acknowledge the assistance of Brooke Roe, Susan Loftus, Diana Paksarian, Jana Colley, and Drs. Erik W. Gunderson, Andrew Bennett, Mikhail Nickita, and Aleksandra Beselman.
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