The discriminative stimulus properties of cocaine and d-amphetamine: the effects of three routes of administration.

Five rhesus monkeys were trained to discriminate intramuscular cocaine (0.25 mg/kg, 10 min presession) from saline. In subsequent tests, intramuscular cocaine (0.03-0.5 mg/kg, 10 min presession) and intravenous cocaine (0.03-0.25 mg/kg, 10 min presession) controlled cocaine-appropriate responding in a dose-dependent manner and all monkeys tested reached training criterion (greater than 90% cocaine-appropriate responses) levels after the higher doses were tested. d-Amphetamine (0.03-0.5 mg/kg) delivered intramuscularly (10 min presession) or intragastrically (60 min presession) also controlled cocaine-appropriate responding in a dose-dependent manner and, at the higher doses, all monkeys tested reached criterion. Regardless of route, cocaine and d-amphetamine were similar in potency. Intragastric cocaine (0.5-16.0 mg/kg, 60 min presession) also controlled cocaine-appropriate responding at some dose in each monkey tested, but the drug was less potent. More importantly, the effects of IG cocaine were less systematic possibly due to uncontrolled pharmacokinetic factors.