Discriminative stimulus effects of cocaine abuse medications in the rhesus monkey

In order to examine the link between the ability of a drug to reduce cocaine intake and the other behavioral effects of these drugs, several drugs were tested in a drug discrimination paradigm. Three rhesus monkeys were trained to discriminate intravenous injections of cocaine (0.1 mg/kg) from saline. The catecholamine releaser phentermine (0.3 to 1 mg/kg) substituted for cocaine in all three subjects, as did d-amphetamine (0.1 to 1.0 mg/kg). The dopamine uptake inhibitor GBR 12909 (0.3 to 1 mg/kg) resulted in predominantly cocaine-appropriate behavior in one subject and entirely cocaine-appropriate behavior in the other two. No dose of buspirone tested (0.03 to 1 mg/kg) resulted in cocaine-appropriate behavior in any subject. These results are consistent with the hypothesis that phentermine, GBR 12909 and d-amphetamine reduce cocaine self-administration by substituting for cocaine.