Genetics, haloperidol and pimozide: a comparative study in two mouse strains

Haloperidol and pimozide are the only medications approved in management of Tourette's syndrome, thought due to dopaminergic overactivity with a possible genetic trait. The effect of equal dose regimens of these drugs on some brain biogenic amines and major acidic metabolites was studied in two genetically different strains of mice. These drugs exerted strain-dependent effect on regional brain levels of the compounds measured. The results suggest a higher turnover of striatal dopamine by haloperidol than by pimozide in the albino BALB/c but not in the black C57BL/6 mouse strain which may explain the high incidences of haloperidol-induced extrapyramidal side effects. Conversely, a greater decrease in serotonin turnover by pimozide than by haloperidol was apparent in two brain regions of C57BL/6 but not in BALB/c mice which may contribute to the unwanted sedative effect reported for pimozide. The results suggest the possible contribution of genetic factors to cerebral potency of these neuroleptics which may explain variable therapeutic response and sensitivity to drug-produced toxicity in Tourette's syndrome.