2% vs 3.9%, P = .006).22 Stiell et al compared methotrimeprazine (not available in the USA) 37.5 mg IM to meperidine 75 mg IV plus dimenhydrinate 50 mg IM.23 There was no significant difference in pain reduction (VAS) for methotrimeprazine vs meperidine/dimenhydrinate (−40.3 vs −46.6, P = .27). There were more reports of prolonged drowsiness with methotrimeprazine (51.7% LY2835219 purchase vs 16.7%; P = .01). Table 2 summarizes the studies involving chlorpromazine, promethazine, and methotrimeprazine. Butyrophenones, neuroleptics acting as potent dopamine receptor antagonists with some antihistamine and anti-serotonergic activity, can rapidly decrease

brainstem activity. They are used as anti-emetics, sedatives, and antipsychotic agents. As with all neuroleptics, the side effects of butyrophenones include akathisia, dystonia, hypotension, dizziness, drowsiness, and drug-induced parkinsonism. Butyrophenones can cause QTc prolongation to a degree where there is increased risk of ventricular arrhythmias and cardiac arrest. There have been 9 cases of torsade de pointes reported in 30 years, and all have been with droperidol at doses of 5 mg IV or greater.24,25 As noted previously, the likelihood of dystonia or drug-induced parkinsonism with butryophenones can be lessened by using concomitant anticholinergic medication. Orthostatic hypotension can be avoided by pretreating with a 500 mL NS bolus. Silberstein

et al compared C59 mouse 4 doses of droperidol IM (0.1, 2.75, 5.5, and 8.25 mg)

to placebo/NS IM.26 The percentages of subjects pain-free at 2 hours for placebo and droperidol doses 0.1, see more 2.75, 5.5, and 8.25 mg were 16, 27, 49, 37, and 34%, respectively (P < .01). Thirty percent of those receiving 2.75 mg or more of droperidol reported serious side effects, including anxiety, akathisia, and somnolence. No patient had ECG changes showing QT prolongation. Miner et al compared droperidol 5 mg IM or 2.5 mg IV to prochlorperazine 10 mg IM or 10 mg IV.27 There was no difference in efficacy between IM and IV routes for either medication. Pain reduction (VAS) at 1 hour was greater for droperidol (−81.4% vs −66.9%; P < .001). Frequency of side effects for droperidol and prochlorperazine were similar (15.2% vs 9.6%; P = .19), with sedation being more common with droperidol (9% vs 1%). Weaver et al also compared droperidol 2.5 mg IV to prochlorperazine 10 mg IV.28 The percentage pain-free at 30 minutes favored droperidol (54.2% vs 37.5%; P < .01), but pain reduction (VAS) was not greater for droperidol (−79.1 vs −72.1; P = .23). The rate of akathisia was similar for both treatments (6% vs 8%; P = .25). Richman et al found droperidol 2.5 mg IM and meperidine 1.5 mg/kg IM produced similar pain reduction (VAS) (−47 vs −37; P = .33); akathisia was reported in 13.3% taking droperidol, with sedation in 6.7% taking droperidol, and 14.3% taking meperidine.