Discriminative stimulus properties and schedule effects of fencamfamine in rats

The behavioral properties of fencamfamine, a sympathomimetic central stimulant recently identified in alleged cocaine samples, were studied in two different paradigms. In Experiment I, rats were trained to discriminate between injections of saline (0.1 ml/kg, IP) and cocaine (3.0 mg/kg, IP) in a two-lever drug discrimination task on a fixed-ratio (FR) 10 schedule of water presentation. Fencamfamine (0.3–3.0 mg/kg, IP) produced cocaine-appropriate choice behavior and was slightly more potent than cocaine in producing this effect. In Experiment II, rats responded under a multiple fixed-interval (FI) 300 sec, FR 20 schedule of water presentation. Fencamfamine (0.1–10.0 mg/kg, IP) and cocaine (0.1–30.0 mg/kg, IP) produced qualitatively similar effects on responding under this schedule. With increasing doses of either drug, FI response rates first increased, then decreased; FR response rates were only decreased. Fencamfamine was approximately three times more potent than cocaine in producing these effects. The results of these two experiments indicate that fencamfamine and cocaine have similar behavioral properties.