Identifying the Lowest Effective Dose of Acetazolamide for the Prophylaxis of Acute Mountain Sickness: Systematic Review and Meta Analysis
It has been well described that acetazolamide, a carbonic anhydrase inhibitor, can be used as prophylaxis for acute mountain sickness (AMS) with a number needed to treat (NNT) to prevent 1 case of AMS ranging from 3 to 7. This medication, however, can have side effects of paresthesias, dysgeusia, polyuria, and rash. Therefore, determining a minimum effective prophylactic dose can decrease adverse effects and improve patient compliance.
The investigators performed a systematic review and meta-analysis of 11 randomized controlled trials using 250 mg, 500 mg, or 750 mg daily doses vs placebo at elevations greater than 3,000 m. It was determined that although all doses were more effective than placebo (combined odds ratio 0.36, with 95% CI: 0.28 to 0.46), the lowest effective dose was 250 mg daily with a NNT of 6. This was a significantly lower dose than the 750 mg (NNT = 3) minimum effective dose published in a prior review of the topic in 2000.
The study is limited by the inability to control between the selected studies for elevation, ascent rate, partial acclimatization before enrollment, or other potential confounders that would lead to differential AMS incidence. Furthermore, AMS severity was not analyzed. The authors noted that the lowest effective dose was the lowest dose studied, identifying a need to investigate lower acetazolamide doses.
(BMJ. 2012) WV Low, AJ Avery, V Gupta, et al.