Self-administration of minaprine in rhesus monkeys

Four rhesus monkeys trained to press levers for intravenous cocaine infusions were tested with saline and minaprine [3-(2-morpholinoethylamino)-4-methyl-6-phenyl pyridazine dihydrochloride, 3-300 micrograms/kg per infusion] during daily 1-h sessions. From 4 to over 25 times more cocaine infusions were obtained than saline infusions during baseline sessions. When minaprine was substituted for cocaine, none of the tested doses maintained responding above saline levels in two of the monkeys. Some doses of minaprine did maintain responding slightly above those of saline in the other two monkeys; however, the average number of infusions and the within-session time course of minaprine infusions at these doses were markedly more similar to saline than to that of cocaine. It was concluded that minaprine did not serve as a positive reinforcer under the present experimental conditions for any of the monkeys and it was predicted that minaprine would have low liability for recreational use in humans.