Dose-Ranging Antiemetic Trial of High-Dose Oral Metoclopramide

The present trial with high oral doses of metoclopramide was undertaken to (a) determine a well-tolerated dosage of oral metoclopramide; (b) measure the blood levels achieved with these oral doses; (c) determine the side effects of high doses; and (d) observe for antiemetic efficacy. Thirty-six patients receiving emesis-producing chemotherapy consisting primarily of high intravenous (i.v.) doses of cyclophosphamide plus adriamycin or cisplatin received 48 courses of oral metoclopramide. The metoclopramide dosage was escalated in six steps from 0.5 to 3.0 mg/kg and was given 1/2 h before chemotherapy, then 1 1/2, 3 1/2, 7 1/2, 11 1/2, and 15 1/2 after chemotherapy. Diphenhydramine (50 mg orally) was given with the first, third, and fifth dosages. Toxicity was generally mild, not dose related, and similar to that observed with the i.v. drug with the exception of an increased incidence of acute dystonic reactions. Antiemetic effects were observed at each dose level. In patients receiving oral metoclopramide doses of 2 or 3 mg/kg, all achieved serum levels greater than 1,000 ng/ml. High-dose oral metoclopramide was well tolerated and demonstrated antiemetic effects at the dose levels explored. We recommend 2-3 mg/kg oral metoclopramide doses with 50 mg diphenhydramine for use in future trials.