Comparison of Methazolamide and Acetazolamide for Prevention of Acute Mountain Sickness in Adolescents

ABSTRACT

PURPOSE: Acute mountain sickness (AMS) commonly occurs when unacclimatized individuals ascend to altitudes above 2500 m. Acetazolamide, a carbonic anhydrase inhibitor (CAI), is recommended for AMS prophylaxis, but may have adverse effects such as paresthesia. Methazolamide has the same pharmacologic effect, but diffuses more rapidly into tissue and is more potent than acetazolamide. But, little is known about methazolamide as an AMS prophylactic agent. This study was conducted to prospectively compare metazolamide with acetazolamide for its preventive effect for AMS in adolescents. METHODS: Nineteen adolescents aged 13~18 years attempting an ascent of Mt. Kalapatar (5500 m) were randomly divided to receive acetazolamide (n=10) or methazolamide (n=9). Oxygen saturation (SpO2) and pulse rate were measured at each altitude. The incidence of AMS was calculated using the Lake Louise questionnaire. Difference in incidence between two groups was analyzed using generalized estimating equation. Difference in Lake Louise scores (LLS) was analyzed using linear mixed model testing. RESULTS: Overall incidence of AMS was 68.4%. Fatigue or malaise was the most frequent symptom (94.7%) followed by headache (84.2%). SpO2 decreased as the altitude increased (p<0.001). There was no difference in SpO2 and pulse rate between the two groups (p=0.44). There was no difference in LLS (p=0.22) and incidence of AMS (p=0.07) between the two groups with increasing altitude. Paresthesia was less common in the methazolamide group, but was not statistically different (p=0.35). CONCLUSION: Methazolamide is equally effective as acetazolamide in preventing AMS among adolescents.