Metoclopramide and haloperidol in tardive dyskinesia.

The effect of single intravenous doses of metoclopramide (10 mg, 20 mg and 40 mg) and haloperidol (5 mg and 10 mg) have been compared to placebo (saline) in a double blind randomised study in 8 patients with tardive dyskinesia secondary to neuroleptic therapy. Tardive dyskinesia rating scores were improved significantly (P less than 0.01) 6 hours after dosing by metoclopramide 40 mg, and haloperidol 5 mg and 10 mg, when compared to placebo. Single doses of dopamine receptor blocking agents improve tardive dyskinesia. The dose of metochlopramide required to show a beneficial effect was high, and this therefore suggests that it is unlikely to be of therapeutic value as the incidence of adverse reactions would be greatly increased. By monitoring the effects of single doses of dopamine receptor blocking drugs in patients with tardive dyskinesia it is possible to compare the relative potencies of these drugs on dopaminergic systems in vivo in man.