Use of a prophylactic antiemetic with morphine in acute pain: randomised controlled trial

Objective: The aim of this study was to compare the incidence of nausea and vomiting in patients with acute pain treated with morphine along with prophylactic metoclopramide or placebo. Method: A randomised controlled trial was carried out on patients requiring morphine for acute pain in the emergency department ( ED) setting. Children under the age of 12, patients who had been vomiting or had already received prehospital analgesia, and those unable to give consent were excluded. All patients were given either metoclopramide ( 10 mg) or placebo ( normal saline) followed by intravenous morphine. Pain scores ( measured on a visual analogue scale) before and after morphine administration, all incidents of nausea or vomiting, the dose of morphine, and the patients' demographic data were recorded. Fisher's exact test was used for comparing the two groups of patients. Results: A total of 259 patients were recruited. There were 123 patients in the metoclopramide group ( age range 15 - 94 years; median age 53) and 136 patients in the placebo group ( age range 17 - 93 years; median age 52.5). The overall incidence of nausea and vomiting in the whole study population was 2.7%, ( 1.6% in the metoclopramide group and 3.7% in the placebo group). The difference between the two groups was not statistically significant ( Fisher's exact test = 0.451; p = 0.3; z- test statistic = 1.02; 95% Cl - 6% to 2%). Conclusion: When intravenous morphine is administered for acute pain, the overall incidence of nausea and vomiting is low, regardless of whether these patients are given prophylactic metoclopramide or not.