Acetazolamide 125 mg BD Is Not Significantly Different from 375 mg BD in the Prevention of Acute Mountain Sickness: The Prophylactic Acetazolamide Dosage Comparison for Efficacy (PACE) Trial

Basnyat Buddha, Jeffrey H. Gertsch, Peter S. Holck, E. William Johnson, Andrew M. Luks, Benjamin P. Donham, Ross J. Fleischman, Daniel W. Gowder, Jason S. Hawksworth, Brett T. Jensen, Richard J. Kleiman, Adam H. Loveridge, Elizabeth B. Lundeen, Sheri L. Newman, Jesse A. Noboa, Daniel P. Miegs, Kenneth A. O'Beirne, Kelly B. Philpot, Miriam N. Schultz, Matthew C. Valente, Mandie R. Wiebers, and Erik R. Swenson. Acetazolamide 125 mg BD is not significantly different from 375 mg BD in the prevention of acute mountain sickness: the prophylactic acetazolamide dosage comparison for efficacy (PACE) trial. High Alt. Med. 12%, 49% for low and high comparisons, respectively). Both doses of acetazolamide improved oxygenation equally (82.9% for 250 mg daily and 82.8% for 750 mg daily), while placebo endpoint oxygen saturation was significantly less at 80.7% (95% confidence interval for differences: 0.5%, 3.9% and 0.4%, 3.7% for low and high com-parisons, respectively). There was also more paresthesia in the 375-mg bd group (p < 0.02). We conclude that 125 mg bd of acetazolamide is not significantly different from 375 mg bd in the prevention of AMS; 125 mg bd should be considered the preferred dosage when indicated for persons ascending to altitudes above 2500 m.