A dose-response study of acetazolamide for acute mountain sickness prophylaxis in vacationing tourists at 12,000 feet (3630 m)

Carlsten, Chris, Erik R. Swenson, Stephen Ruoss. A dose-response study of acetazolamide for acute mountain sickness prophylaxis in vacationing tourists at 12,000 feet (3630 m). High Alt. Med. Biol. 5:33-39, 2004.-The study objective was to determine whether acetazolamide is effective in prophylaxis of acute mountain sickness (AMS) at moderate altitude in ambulatory travelers not undergoing vigorous exercise. Volunteers vacationing in La Paz, Bolivia (3630 m), immediately after arrival from sea level were studied. The design was a double-blind, randomized trial of two doses of acetazolamide (125 mg twice daily, 250 mg twice daily) versus placebo twice daily over a 24-h period. The main outcome measure was AMS score and score trend, using the Lake Louise consensus questionnaire. Nine of 32 subjects (28%) had symptom scoring diagnostic of AMS at 0 h. At 0 and 24 h (respectively), the mean Lake Louise scores were 1.73 and 1.09 for the 11 subjects receiving placebo, 1.45 and 1.36 for the 11 subjects receiving the 125-mg dose, and 2.7 and 0.6 for the 11 subjects receiving the 250-mg dose. The absolute change in these mean scores was not significant for placebo (p = 0.21) or the 125-mg dose (p = 0.88), but was significant for the 250-mg dose (p = 0.008). A comparison of a difference in decline in average AMS score over time showed a statistically significant decline for the 250-mg dosing group versus placebo (p = 0.002). The 250-mg dose of acetazolamide twice daily (but not 125 mg twice daily) was effective in inducing a significant decline in AMS symptoms over the 24-h period after arrival to 3630 m. These results suggest that the dosing of acetazolamide for AMS prevention in nonmountaineering tourists at altitudes below 3700 m should not be lowered below 250 mg twice daily.