Effect of Acetazolamide on Acute Mountain Sickness in Lowlanders Older Than 40 Years

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Brief Title

Effect of Acetazolamide on Acute Mountain Sickness in Lowlanders Older Than 40 Years

Official Title

Acetazolamide for Prevention of Acute Mountain Sickness in Healthy Lowlanders Older Than 40 Years. Randomized Trial.

Brief Summary

      Randomized, placebo controlled trial evaluating efficacy of acetazolamide in preventing acute
      mountain sickness in lowlanders older than 40 years travelling from 760 m to 3'100 m.

Detailed Description

      This is a randomized, placebo-controlled, double-blind parallel trial evaluating the efficacy
      of acetazolamide prophylaxis in reducing the incidence of acute mountain sickness (AMS) in
      lowlanders older than 40 years travelling to altitude. Participants living in the Bishkek
      area, Kyrgyzstan (760m), will be transferred by car within 4h to the Tuja Ashu high altitude
      clinic (3'100 m), and stay there for 2 days. Acetazolamide 375mg/day (or placebo), will be
      administered before departure at 760 m and during the stay at altitude. Outcomes will be
      assessed during the stay at 3'100 m.

      An interim analysis will be carried out when 80 participants will have completed the study or
      after the first year. The Peto's method will be used and the trial will be stopped when
      pre-specified futility boundaries were crossed.

Study Phase

Phase 4

Study Type


Primary Outcome

Acute mountain sickness (AMS), incidence

Secondary Outcome

 Acute mountain sickness (AMS), severity assessed by the Lake Louise score


Acute Mountain Sickness


ACETAZOLAMIDE oral capsule

Study Arms / Comparison Groups

 ACETAZOLAMIDE oral capsule
Description:  Acetazolamide 375mg/day (capsule @125 mg: 1 in the morning, 2 in the evening), orally. Medication starts 24 hours before ascent to 3'100m until the morning after the second night at 3'100m


* Includes publications given by the data provider as well as publications identified by National Clinical Trials Identifier (NCT ID) in Medline.

Recruitment Information

Recruitment Status


Estimated Enrollment


Start Date

June 1, 2018

Completion Date

December 31, 2020

Primary Completion Date

December 31, 2020

Eligibility Criteria

        Inclusion Criteria:

          -  Healthy men and women, age 40-75 yrs, without any disease and need of medication.

          -  Born, raised and currently living at low altitude (<800m).

          -  Written informed consent.

          -  Kyrgyz ethnicity

        Exclusion Criteria:

          -  Any active respiratory, cardiovascular or other disease requiring regular treatment or
             being otherwise relevant for tolerance of hypoxia or altitude exposure.

          -  Any condition that may interfere with protocol compliance including current heavy
             smoking (>20 cigarettes per day or >20 pack-years with active smoking during the last
             10 years), regular use of alcohol.

          -  Allergy to acetazolamide and other sulfonamides.




40 Years - 75 Years

Accepts Healthy Volunteers

Accepts Healthy Volunteers


Konrad E Bloch, MD, , 

Location Countries


Location Countries


Administrative Informations



Organization ID


Responsible Party


Study Sponsor

University of Zurich


 National Center of Cardiology and Internal Medicine named after academician M.Mirrakhimov

Study Sponsor

Konrad E Bloch, MD, Study Chair, University Hospital, Zürich

Verification Date

January 2020