Sickness Evaluation at Altitude With Acetazolamide at Relative Dosages

Learn more about:

Brief Title

Sickness Evaluation at Altitude With Acetazolamide at Relative Dosages

Official Title

Sickness Evaluation at Altitude With Acetazolamide at Relative Dosages

Brief Summary

      This double blind randomized trial will compare acetazolamide taken the morning of ascent to
      acetazolamide taken the evening prior to ascent for the prevention of acute mountain sickness
      (AMS). The day of ascent dosing has not been studied as a powered primary outcome. The study
      population is hikers who are ascending at their own rate under their own power in a true
      hiking environment at the White Mountain Research Station, Owen Valley Lab (OVL) and Bancroft
      Station (BAR), Bancroft Peak, White Mountain, California

Detailed Description

      The specific aim of this study is to determine whether acetazolamide started the day-of
      ascent is inferior to the standard night before ascent dose of acetazolamide for the
      prevention of acute mountain sickness (AMS) in travelers in travelers to high altitude.
      Acetazolamide has been examined in over 200 high altitude studies over the past 50 years, and
      is the most commonly used drug for AMS prevention in the high mountains of Nepal, Western
      Europe, and Africa. Current Wilderness Medical Society Practice Guidelines recommend a 125mg
      dose of acetazolamide daily started the day or evening prior to ascent. However, day of
      ascent dosage has recently been found to be effective prophylaxis for severe AMS compared to
      placebo, but efficacy of day-of ascent dosage has not be confirmed versus standard
      acetazolamide dosage.

      While acetazolamide is commonly used as an acclimatization aid, it is traditionally started
      the day or evening prior to ascent to theoretically optimize diuretic effect and compensatory
      respiratory changes. This timing may be impractical when rapid ascent is necessary, such as
      in search and rescue and military operations, or for the general recreationalists, trekkers,
      or climbers who do not have time to start prophylaxis prior to heading into the mountains. As
      there are an estimated 100 million recreationalists annually who ascend to high altitude
      around the world, innovation on optimal timing has a potentially large impact on traveler

      Acetazolamide has a time of onset between 60 - 90 minutes when taken as an immediate release
      tablet, with peak effect between 2 - 4 hours. With these pharmacokinetics in mind, we
      recently found that there was an observed robust protective effect of acetazolamide on severe
      AMS when taken the morning of ascent, and this was the first study to examine day-of dosing.
      This novel finding has not been otherwise investigated, and confirmation of this unique
      observation has the potential to increase acetazolamide'sits usage in "high risk" populations
      maximizing safety, while minimizing discomfort and poor sleep from pre-ascent nocturia., such
      as trekkers, skiers, climbers, and tactical missions requiring rapid ascents in the mountains
      of North America and Europe.

Study Phase

Phase 1

Study Type


Primary Outcome

incidence of acute mountain sickness


Acute Mountain Sickness



Study Arms / Comparison Groups

 day of acetazolamide
Description:  acetazolamide 125mg twice a day, started morning of ascent


* 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

August 4, 2018

Completion Date

September 30, 2018

Primary Completion Date

September 30, 2018

Eligibility Criteria

        Inclusion Criteria:

          -  Age 18-75 healthy non-pregnant volunteer

          -  live at low elevation < 4000 ft

          -  Arrange your own transportation to WMRS (Bishop) by Friday evening of study weekend

          -  Available for full study duration (Friday PM-Sunday AM)

        Exclusion Criteria:

          -  Age <18 or >75, Pregnant, Live at altitude >4000 ft Slept at altitude > 4000ft within
             1 week of study Allergic to acetazolamide, sulfa drugs, Taking non-steroidal
             anti-inflammatory drugs, Acetazolamide, or Corticosteroids 1 week prior to study




18 Years - 75 Years

Accepts Healthy Volunteers

Accepts Healthy Volunteers


, , 

Location Countries

United States

Location Countries

United States

Administrative Informations



Organization ID


Responsible Party

Principal Investigator

Study Sponsor

Stanford University

Study Sponsor

, , 

Verification Date

November 2018