Sulpiride in tardive dyskinesia

Tardive dyskinesia can be suppressed by drugs that block dopaminergic receptors, but often at the cost of a concomitant increase in parkinsonism. Sulpiride (400-2100 mg/day), a selective type-2 dopamine receptor antagonist, was evaluated in a blind, placebo-controlled trial in 11 patients with tardive dyskinesia. It significantly (P<0.01) reduced tardive dyskinesia without significantly affecting parkinsonism, although three patients had an increase in preexisting parkinsonian hypokinesia and tremor, During the placebo phase, the tardive dyskinesia and parkinsonian scores returned to the pretreatment values. There was no relationship between either tardive dyskinesia or parkinsonism and eye blinking rates. These results are consistent with the hypothesis that more than one population of dopamine receptors are involved in controlling extrapyramidal functions. Sulpiride is an important tool for elucidating both the practical and heuristic aspects of subtypes of dopamine receptors and is a lead in the search for compounds that selectively affect dopaminergic mechanisms.