THE DISCRIMINATIVE STIMULUS EFFECTS OF TRIPELENNAMINE IN HUMANS

Twenty volunteers were trained to discriminate between 75 mg tripelenn amine (TP) and placebo, During the first four sessions, the drugs were identified prior to ingestion by letter code, During the next is sess ions, the procedure was the same except the capsules were not identifi ed. At the end of the 3-h session, participants indicated which capsul e they believed they received using the letter codes, When correct, th ey received a monetary bonus. If they were correct on five sessions, t hey entered the third phase which had tell additional training and 12 test sessions. During tests, participants received capsules that conta ined other drugs, including diphenhydramine (50 and 75 mg), chlorpheni ramine (4 and 6 mg), diazepam (5 and 10 mg), d-amphetamine (5 and 10 m g), as well as tripelennamine (25, 50 and 75 mg) and placebo. Thirteen participants learned the discrimination and nine entered the third ph ase, Except for placebo, most participants identified the test compoun ds as TP and labeled them as sedatives. TP produced significant change s on several subjective and physiological measures. The test compounds produced varied effects which were neither clearly dose-related nor r elated to the identification as TP or placebo, These results indicate that tripelennamine call function as a discriminative stimulus, but wi th little evidence of pharmacological specificity.