Prochlorperazine versus promethazine for uncomplicated nausea and vomiting in the emergency department: A randomized, double-blind clinical trial

Study objective: Nausea and vomiting related to gastritis or gastroenteritis are common complaints in the emergency department. The most effective antiemetic agent is yet undetermined. This study was conducted to compare the efficacy of prochlorperazine versus promethazine for uncomplicated nausea and vomiting in the ED. Methods: The study was a randomized, double-blind comparison of prochlorperazine (Compazine) and promethazine (Phenergan) for acute ED treatment of gastritis or gastroenteritis. We studied patients 18 years or older with presumed uncomplicated gastritis or gastroenteritis who presented to 2 academic EDs. Patients were randomly assigned to receive either prochlorperazine, 10 mg intravenously, or promethazine, 25 mg intravenously. Visual analog scale readings of patient comfort were obtained at baseline and at 30- and 60-minute intervals. The primary endpoint was degree of relief at 30 and 60-minutes. Secondary endpoints were time to complete relief, need for further antiemetic medication (treatment failures), and side effects. Statistical analysis was performed using the Mann-Whitney U test for nonparametric analysis and repeated-measures analysis of variance (ANOVA). Results: Eighty-four patients were enrolled in the study; 42 received prochlorperazine and 42 received promethazine. There were no differences in demographics in the 2 groups. At baseline (time 0), there was no difference in symptoms (P=.23). At 30 and 60 minutes after receiving medication, prochlorperazine worked significantly better than promethazine (P=.004 and P<.001 using nonparametric analysis). Using repeated-measures ANOVA, there was a significant difference in symptoms over time for both groups (P<.001) and a significant difference in prochlorperazine versus promethazine (P=.002). Time to complete relief was significantly shorter with prochlorperazine (P=.021). There were significantly fewer treatment failures with prochlorperazine (P=.03, 9.5% versus 31%, difference 21%, 95% confidence interval 5 to 38). There was no difference in incidence of extrapyramidal effects. Prochlorperazine caused significantly fewer complaints of sleepiness (P=.002. 38% versus 71%, difference 33%, 95% confidence interval 13 to 53; P=.002). Conclusion: Prochlorperazine works significantly better than promethazine for relieving symptoms of nausea and vomiting more quickly and completely in ED patients with uncomplicated nausea and vomiting.