A randomised double-blind study of high-dose intravenous prochlorperazine versus high-dose metoclopramide as antiemetics for cancer chemotherapy.

High-dose prochlorperazine 0.8 mg/kg administered intravenously 30 min pre and 7 h 30 min post the initial dose of emetogenic chemotherapy was compared to high-dose metoclopramide 2 mg/kg over 20 min every 2 h for five doses starting 30 min prior to chemotherapy in a randomised, double-blind, parallel subjects design study. On the prochlorperazine arm intravenous dextrose placebos every 2 h maintained blinding. Complete suppression of vomiting occurred in 42% on metoclopramide (53% with non-cisplatin regimens) and 36% on prochlorperazine (52% with non-cisplatin-containing regimens) while major responses (2 or less vomits) occurred in 58% on metoclopramide and 54% on prochlorperazine. In patients who vomited after cisplatin, prochlorperazine achieved a significantly shorter duration of vomiting, a median of 5 h compared to 15 h on metoclopramide (P = 0.03). The response rate to prochlorperazine for cisplatin-induced emesis between 12 and 24 h was significantly better than for metoclopramide (prochlorperazine = 0.02). Toxicities were equivalent except for significantly greater sedation and dry mouth on prochlorperazine. Extrapyramidal reactions were recorded equally on both arms but were only severe enough to stop treatment on metoclopramide. The metoclopramide regimen was five times as expensive as prochlorperazine. High-dose prochlorperazine is an active and cost-effective antiemetic.