Comparison of phencyclidine and three analogues on fixed-interval performance in rhesus monkeys

The effects of four arylcyclohexylamines on operant performance in rhesus monkeys were compared. Four rhesus monkeys were trained to lever press on a multiple fixed-interval 5 min time out 1 min schedule of food presentation during daily 1 1/2 hour sessions. Dose-response curves and median effective doses were determined for phencyclidine, N-ethyl-1-phenylcyclohexylamine, 1-(1-(2-thienyl) cyclohexyl) piperidine and ketamine. Ketamine was found to be approximately 1/10 as potent as the other drugs which were approximately equipotent. The drugs had qualitatively similar effects. High doses of all four drugs decreased overall response rates and the slopes of the dose-response curves were comparable. A dose-related rate-dependent effect was found for all four drugs. Onset and duration of the drug effects were also presented.