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Acetazolamide for the Prevention of High Altitude Illness: a Comparison of Dosing

Information source: University of Utah
ClinicalTrials.gov processed this data on August 20, 2015
Link to the current ClinicalTrials.gov record.

Condition(s) targeted: Prophylaxis of Acute Mountain Sickness

Intervention: Acetazolamide (Drug)

Phase: Phase 4

Status: Recruiting

Sponsored by: University of Utah

Official(s) and/or principal investigator(s):
McIntosh Scott, MD, Principal Investigator, Affiliation: University of Utah


Acetazolamide, or Diamox, is the standard medical prophylaxis agent for high altitude illness. The medication is effective in preventing acute mountain sickness (AMS), high altitude pulmonary edema (HAPE), and high altitude cerebral edema (HACE). Its mechanism is via inhibition of the carbonic anhydrase enzyme which counteracts the respiratory alkalosis which occurs during ascent to altitude. It facilitates the excretion of bicarbonate in the urine. As a result, acetazolamide hastens acclimatization and helps prevent high altitude disorders. Current recommended dosing is 125 mg, orally twice daily, started 24 hours prior to ascending in elevation. Side effects include tingling of the fingers and toes and perioral numbness which may be erroneously interpreted as stroke symptoms. Since acetazolamide is a mild diuretic, frequent micturition may occur leading to interruption of daytime activities as well as broken sleep. These effects can affect safety at high altitude. Acetazolamide is normally discontinued 2 days after the user has reached their highest elevation or a plateau in elevation. A lower dose may be just as effective in preventing high altitude illnesses while preventing the disconcerting side effects resulting from its use. A smaller dose has not been studied, however. We will compare the common dose of 125 mg twice daily with a lower dose of 62. 5 mg twice daily.

Clinical Details

Official title: Acetazolamide for the Prevention of High Altitude Illness: a Comparison of Dosing

Study design: Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Investigator), Primary Purpose: Treatment

Primary outcome: Prevention of acute mountain sickness as measured by the Lake Louise Score

Secondary outcome: Side effect profile of acetazolamide


Minimum age: 18 Years. Maximum age: N/A. Gender(s): Both.


Inclusion Criteria:

- 18 years or older

- English or Indian speaking

- Mountaineers or trekkers who plan to climb Mt. McKinley or trek to Base Camp on Mt.

Everest Exclusion Criteria:

- Low sodium and/potassium blood serum levels

- Kidney disease or dysfunction

- Liver disease, dysfunction, or cirrhosis

- Suprarenal gland failure or dysfunction

- Hyperchloremic acidosis

- Angle-closure glaucoma

- Taking high dose aspirin (over 325 mg/day)

- Any reaction to sulfa drugs or acetazolamide

- Pregnant or lactating women

Locations and Contacts

University of Utah Health Sciences Center, Salt Lake City, Utah 84132, United States; Recruiting
Scott McIntosh, MD, Email: scott.mcintosh@hsc.utah.edu
Scott McIntosh, MD, Principal Investigator
Additional Information

Starting date: March 2012
Last updated: May 26, 2015

Page last updated: August 20, 2015

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