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Prochlorperazine vs. Promethazine for Headache Relief

Prochlorperazine might provide relief sooner and with less drowsiness.

Prochlorperazine has been shown to be more effective than metoclopramide for acute migraine, but prochlorperazine is associated with akathisia in about one third of patients (JW Nov 14 1995 and JW Emerg Med Jan 2 2002). In a randomized, double-blind study, researchers compared efficacy and side effects of intravenous prochlorperazine (10 mg) and IV promethazine (25 mg) in patients who presented to a single emergency department with benign headache. Patients with fever, trauma, or neurological deficit or who reported the "worst headache of their lives" were excluded; 70 patients were enrolled. Diphenhydramine (25 mg) was administered for symptoms of dystonia or akathisia.

Thirty minutes after drug administration, significantly more patients in the prochlorperazine group than in the promethazine group (69% vs. 39%) had a clinically meaningful decrease in headache intensity (defined as a reduction of 25 mm on a 100-mm visual analog scale). However, the magnitude of the change (mean reduction, 36.4 vs. 23.7 mm, respectively) did not differ significantly between groups. Rates of akathisia, use of rescue medications, patient satisfaction, and recurrence of pain within 5 days after discharge were similar between groups. Drowsiness within 1 day after ED discharge was significantly more common in the promethazine group (71% vs. 40%). One third of patients in each group required rescue treatment with diphenhydramine for dystonic reactions or akathisia; rescue treatment was successful in all patients.

Comment: Promethazine is known to cause severe necrosis with inadvertent arterial injection (recently the subject of a multimillion-dollar award), and this study certainly does not support its use. Prochlorperazine is a first-line agent for acute migraine treatment, provided that patients are educated about akathisia and given oral diphenhydramine to take if symptoms develop.

— Aaron E. Bair, MD, MSc, FAAEM, FACEP

Published in Journal Watch Emergency Medicine November 14, 2008

Citation(s):

Callan JE et al. Prochlorperazine vs. promethazine for headache treatment in the emergency department: A randomized controlled trial. J Emerg Med 2008 Oct; 35:247.

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