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

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ClinicalTrials.gov Identifier: NCT01993667
Recruitment Status : Completed
First Posted : November 25, 2013
Results First Posted : January 29, 2019
Last Update Posted : January 29, 2019
Information provided by (Responsible Party):
Scott McIntosh, University of Utah

Brief Summary:
This is a phase 4, randomized, double-blinded interventional trial comparing alternative doses of Acetazolamide for the prevention of High Altitude Illness.

Condition or disease Intervention/treatment Phase
Prophylaxis of Acute Mountain Sickness Drug: Low Dose Acetazolamide Drug: Normal Dose Acetazolamide Phase 4

Detailed Description:

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.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 130 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary Purpose: Treatment
Official Title: Acetazolamide for the Prevention of High Altitude Illness: a Comparison of Dosing
Study Start Date : March 2012
Actual Primary Completion Date : November 2016
Actual Study Completion Date : November 2016

Arm Intervention/treatment
Active Comparator: Acetazolamide normal dose
Experimental : Acetazolamide 125 mg twice daily
Drug: Normal Dose Acetazolamide
Administration of normal dose acetazolamide
Other Name: Diamox

Experimental: Acetazolamide low dose
Experimental: Acetazolamide 62.5 mg twice daily
Drug: Low Dose Acetazolamide
Administration of low dose acetazolamide
Other Name: Diamox

Primary Outcome Measures :
  1. Number of Participants With Acute Mountain Sickness as Measured by the Lake Louise Score [ Time Frame: 12 days ]
    Lake Louise Score, A total score of 3 to 5 indicates mild AMS. A score of 6 or more signifies severe AMS. Minimum value - 0, Maximum = 15

Secondary Outcome Measures :
  1. Number of Participants With Side Effects [ Time Frame: 12 days ]

    The typical side effects of acetazolamide will be measured daily (paresthesias of fingers and toes, change in urination frequency, and change in taste of beverages).

    The side effect questionnaire included the following questions: In the past 12 h, have you experienced the following symptoms: Tingling of toes? Tingling of fingers? Increase in urination? Taste change of beverages? Symptoms were self-reported and rated on a 0-5 scale (0=none, 5=maximum)

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

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

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT01993667

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United States, Utah
University of Utah Health Sciences Center
Salt Lake City, Utah, United States, 84132
Sponsors and Collaborators
University of Utah
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Principal Investigator: McIntosh Scott, MD University of Utah
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Responsible Party: Scott McIntosh, Associate Professor, University of Utah
ClinicalTrials.gov Identifier: NCT01993667    
Other Study ID Numbers: 50402
First Posted: November 25, 2013    Key Record Dates
Results First Posted: January 29, 2019
Last Update Posted: January 29, 2019
Last Verified: January 2019
Additional relevant MeSH terms:
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Altitude Sickness
Respiration Disorders
Respiratory Tract Diseases
Carbonic Anhydrase Inhibitors
Enzyme Inhibitors
Molecular Mechanisms of Pharmacological Action
Natriuretic Agents
Physiological Effects of Drugs