Effects of intravenous metoclopramide in 81 patients with tardive dyskinesia.

We compared acute effects of single intravenous administrations of metoclopramide (40 mg) and placebo in a double-blind crossover study involving 81 patients with tardive dyskinesia. Metoclopramide produced significantly greater reduction in mean total Abnormal Involuntary Movement Scale score as well as in ratings for six of the seven body areas, when compared with placebo. On adjusting each patient's metoclopramide response for his or her placebo response, we found that 35 of the 81 patients had 50% or greater placebo-corrected improvement. There were no apparent clinical differences between metoclopramide responders and nonresponders. Administration of 60 mg of metoclopramide to 15 patients produced greater improvement in tardive dyskinesia as compared with 40 mg; the incidence of acute dystonia, however, jumped from 10% with 40 mg to 33% with 60 mg.