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


CONCLUSIONS
These data indicate that oral Delta(9)-THC may have modest abuse liability in experienced marijuana smokers.
Hart
Carl L
CL
Division on Substance Abuse, New York State Psychiatric Institute and Department of Psychiatry, College of Physicians, Surgeons of Columbia University, NY 10032, USA. clh42@columbia.edu
Haney
Margaret
M
Vosburg
Suzanne K
SK
Comer
Sandra D
SD
Foltin
Richard W
RW
D000284:Administration, Oral; D000328:Adult; D002214:Capsules; D002755:Choice Behavior / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D013759:Dronabinol / Q000008:administration & dosage / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008385:Marijuana Smoking; D011619:Psychotropic Drugs / Q000008:administration & dosage / Q000494:pharmacology; D012055:Reinforcement Schedule; D011795:Surveys and Questionnaires; D013647:Task Performance and Analysis; D014040:Token Economy
D002214:Capsules; D011619:Psychotropic Drugs; D013759:Dronabinol