Acute dyskinesias in monkeys elicited by halopemide, mezilamine and the "antidyskinetic" drugs, oxiperomide and tiapride

Oxiperomide and tiapride are Dopamine Receptor antagonists claimed to have "antidyskinetic" properties in animal models and the clinic. Halopemide and mezilamine are other dopamine antagonists predicted to lack extrapyramidal side effects in man on the basis of animal studies. Acute dyskinesias, a neuroleptic-induced acute extrapyramidal syndrome, were elicited in squirrel monkeys by oxiperomide (1 mg/kg), tiapride (30 mg/kg), and halopemide (10 mg/kg). The dyskinesias were virtually indistinguishable from those caused by a standard behaviorally equivalent dose of haloperidol (1.25 mg/kg PO) in the same individual monkeys. Mezilamine (0.3 mg/kg) also induced dyskinesias, which appeared to be less pronounced than those following haloperidol. The antidyskinetic properties of oxiperomide and tiapride evidently do not confer protection against dyskinetic movements induced by dopamine antagonism.