The atypical neuroleptic, clozapine, exerts antidystonic activity in a mutant hamster model. Comparison with haloperidol.

The effects of the atypical neuroleptic clozapine were studied in an inbred line of Syrian golden hamsters with generalized dystonia, i.e. a frequent movement disorder in humans. The effects of clozapine were compared with those of the classical neuroleptic, haloperidol. Clozapine, 7.5-20 mg/kg i.p., potently reduced the severity of dystonic attacks in the mutant hamster model, but induced marked sedation at these doses. Lower doses were ineffective. Haloperidol, 0.5 mg/kg i.p., significantly reduced the severity of dystonia without marked sedation. The finding that clozapine possesses antidystonic potency similar to that of haloperidol in a genetic model of dystonia might suggest that this atypical neuroleptic is an effective alternative in the treatment of dystonic patients who respond to neuroleptics, particularly because of the clinical evidence that clozapine is almost devoid of extrapyramidal adverse effects.