EFFECTS OF D-AMPHETAMINE AND CAFFEINE IN HUMANS UNDER A COCAINE DISCRIMINATION PROCEDURE

This study examined further the pharmacological specificity of an oral cocaine discriminative stimulus in humans. Five male cocaine-abusing volunteers (two African-American/three Caucasian) were trained to disc riminate between a low dose of cocaine hydrochloride (80 mg/70 kg, p.o .) and placebo. Once the criterion for discrimination was met (i,e, gr eater than or equal to 80% correct responding for four consecutive ses sions), dose-effect curves were determined for the dopamine reuptake i nhibitor cocaine (20, 40, 80, 120 mg/70 kg, p,o,), the indirect dopami ne agonist d-amphetamine (5, 10, 20 mg/70 kg, p.o.) and the adenosine antagonist caffeine (150, 300, 600 mg/70 kg, p,o,), Cocaine, d-ampheta mine and caffeine each produced dose-related increases in cocaine-appr opriate responding. Each compound produced at least a trend towards in creases in a few stimulant-like self-reports and vital signs. When the relationship between cocaine-appropriate responding and self-reports were examined, cocaine and d-amphetamine, but not caffeine, had a simi lar profile of significant associations between discriminative perform ance and stimulant-like self-reports. These results suggest that, alth ough the cocaine discriminative stimulus (80 mg/70 kg) is not specific only to stimulants with primarily dopaminergic actions, its pharmacol ogical specificity may be more clearly defined when the relationship b etween discrimination and self-reports is examined, Behav Pharmacol 19 98; 9:207-217 (C) 1998 Lippincott-Raven Publishers.