Discriminative stimulus, self-reported and cardiovascular effects of orally administered cocaine in humans

AH Oliveto, MI Rosen, SW Woods and TR Kosten

Division of Substance Abuse, Connecticut Mental Health Center, Yale School of Medicine, New Haven.

This study evaluated whether an oral dose of cocaine can serve as a discriminative stimulus in humans. Four male and one female cocaine- abusing volunteers (ages 26-41 years) were trained to discriminate between cocaine HCl (80 mg/70 kg p.o.) and placebo. Once the criterion for discrimination was met (i.e., > or = 80% correct responding for four consecutive sessions), dose-effect curves were determined for orally administered cocaine (20, 40, 80 and 120 mg/70 kg), intranasally administered cocaine (20, 40, 80 and 120 mg/70 kg) and the benzodiazepine triazolam (0.25 and 0.50 mg/70 kg p.o.). All five subjects met the criterion for the cocaine-placebo discrimination within four to seven sessions. Novel cocaine doses by either the oral or intranasal route of administration generally produced dose-related increases in cocaine-appropriate responding, whereas triazolam produced predominantly placebo-appropriate responding. Cocaine by both routes produced qualitatively similar increases in stimulant-like self- reports, blood pressure and heart rate, whereas triazolam produced increases in sedative-like ratings and no changes in cardiovascular measures. Throughout dose-effect curve determinations, the training dose of cocaine and placebo continued to be identified correctly in four of five subjects (range, 75-100% correct responding). These results suggest that orally administered cocaine (80 mg/70 kg) is discriminable from placebo, has behavioral effects that are qualitatively similar to intranasal cocaine and does not show cross- generalization to a pharmacologically dissimilar compound.

Volume 272, Issue 1, pp. 231-241, 01/01/1995
Copyright © 1995 by American Society for Pharmacology and Experimental Therapeutics

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