Diazepam vs. Meclizine (the fight that will leave your head spinning)
The Article: Diazepam and Meclizine Are Equally Effective in the Treatment of Vertigo: An Emergency Department Randomized Double-Blind Placebo-Controlled Trial. Shih RD et al. J Emerg Med. 2017 Jan;52(1):23-27.
The Idea: Comparing diazepam vs. meclizine for treatment of peripheral vertigo
The Study: This was a prospective, double-blind trial performed in a single suburban ED using a randomized convenience sample. Patients were randomized to take either 5 mg of diazepam or 25 mg of meclizine orally. Patients recorded their levels of vertigo on a 100 mm visual analog scale prior to treatment, thirty minutes and sixty minutes after treatment. The study was powered to detect a difference of 20 on a 100 mm visual analog scale for vertigo with an n=40 (twenty in each group). There was no placebo control group, despite the title of this article.
The Results: The mean t0 score was 55 mm for the diazepam group and 62 for the meclizine group. No significant differences in the average decrease was observed between groups at any time point. At t60 the mean improvement in the diazepam and meclizine groups were 36 and 40 mm respectively.
The Takeaway: The authors conclude that meclizine and diazepam are equally effective for the treatment of vertigo, but this is a small study not powered to detect small differences. Additionally, the data supporting their use at all above placebo is barely there. The only placebo-controlled study supporting the use the meclizine for the treatment of peripheral vertigo was from 1972 (1). The only study comparing diazepam to placebo was from 1980 (2), and demonstrated no effect to long term therapy. The article we looked at today would have been much stronger if it had a placebo control as the title implies or even ORM (otolith repositioning maneuver) as a control.
Meclizine and Placebo in Treating Vertigo of Vestibular Origin Relative Efficacy in a Double-Blind Study. Bernard Cohen, MD; J. M. B. Vianney deJong, MD. Arch Neurol. 1972;27(2):129-135. doi:10.1001/archneur.1972.00490140033006
Lorazepam and diazepam in the treatment of benign paroxysmal vertigo. McClure JA, Willett JM. J Otolaryngol. 1980 Dec;9(6):472-7.