A comparison of two differing doses of promethazine for the treatment of postoperative nausea and vomiting.

PURPOSE To compare the use of promethazine 6.25 mg intravenous (IV) (experimental group) with promethazine 12.5 mg IV (control group) among adult ambulatory surgery patients to control established postoperative nausea or vomiting (PONV). DESIGN/METHODS In a double-blind, randomized controlled trial (n = 120), 59 subjects received promethazine 6.25 mg and 61 subjects received promethazine 12.5 mg to treat PONV. Study doses were administered postoperatively if the subject reported/exhibited nausea and/or vomiting. Outcomes for experimental and control groups were compared on the basis of relief of PONV and sedation levels. FINDINGS Ninety-seven percent of subjects reported total relief of nausea with a single administration of promethazine at either dose. Sedation levels differed between groups at 30 minutes post-medication administration and at the time of discharge to home. CONCLUSIONS Promethazine 6.25 mg is as effective in controlling PONV as promethazine 12.5 mg, while resulting in less sedation.