Evaluation of the abuse liability of aminorex

Aminorex is a cyclic phenylisopropylamine that has been marketed as an anorectic. Despite obvious pharmacological similarities to the amphetamines, little is known about its liability for abuse. In the present study, one group of rhesus monkeys (n = 3) was prepared with intravenous catheters and allowed to self-administer either methohexital or saline in daily experimental sessions. When methohexital and saline self-administration were stable and clearly different, various doses of aminorex (0.001-0.1 mg/kg/injection) were made available for self-administration. Aminorex maintained self-administration above that maintained by saline and slightly lower than that maintained by methohexital in all monkeys. The discriminative stimulus effects of aminorex were evaluated in rhesus monkeys trained to discriminate d-amphetamine (n = 3) or pentobarbital (n = 4) from saline. Aminorex substituted completely for d-amphetamine as a discriminative stimulus but engendered little or no pentobarbital-appropriate responding. Aminorex stimulated locomotor activity in mice and exacerbated the withdrawal syndrome in rats that were dependent upon pentobarbital. These findings indicate that aminorex is a psychomotor stimulant that would be predicted to have significant d-amphetamine-like abuse liability in humans.