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Acute Mountain SicknessPhase 4NCT03561675

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

A Phase 4 study testing ACETAZOLAMIDE oral capsule in people with Acute Mountain Sickness, run by University of Zurich at 1 site in Kyrgyzstan.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial 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. Read more about this study

Who is it for?
Ages 40 to 75 yearsHealthy volunteers can take part
Conditions the study is for
Acute Mountain Sickness
What is being tested?
ACETAZOLAMIDE oral capsule
Type of treatment
Pill or oral medicine
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
349 participants
Where
1 siteKyrgyzstan
Study dates
15 May 2018to 31 Aug 2019
Phase
Phase 4
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 40 to 75 years
  • All sexes
  • Healthy volunteers accepted
  • Adult, Older adult

Who may be able to join

  • 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

Who cannot join

  • 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.

Trial locations and contacts

1 site in 1 country.

Kyrgyzstan1 site

  • National Center of Cardiology and Internal Medicine

    Bishkek, 720040

Other trials in Kyrgyzstan

About this study

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

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.

Read the 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.

Being tested
ACETAZOLAMIDE oral capsule, Placebo oral capsule
Keywords
healthy participants older than 40 years, altitude, prevention, acetazolamide
Medical subject headings
Altitude Sickness

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • ACETAZOLAMIDE oral capsuleDrug

    Administration of 1x125mg acetazolamide in the morning, 2x125mg in the evening, starting 24 hours before departure to 3'100m

  • Placebo oral capsuleDrug

    Administration of equally looking placebo capsules in the morning and evening, starting 24 hours before departure to 3'100m

Study groups in NCT03561675
Study groupRoleWhat they receive
ACETAZOLAMIDE oral capsuleActive comparatorAcetazolamide 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
Receives: Drug: ACETAZOLAMIDE oral capsule
PLACEBO oral capsulePlacebo comparatorPlacebo (capsules identically looking as acetazolamide capsules: 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.
Receives: Drug: Placebo oral capsule

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Acute mountain sickness (AMS), incidence

    Difference between acetazolamide and placebo group in the incidence of AMS during the stay at 3'100 m.

    Measured: Day 1 to 3 at 3'100m

Secondary outcomes (6)

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

    Difference between acetazolamide and placebo group in the severity of AMS during the stay at 3'100 m. The severity of acute mountain sickness (AMS) will be assessed by the Lake Louise questionnaire (LLS), a validated questionnaire about AMS. The severity will be calculated when the presence of headache and at least one of the following symptoms is present: gastrointestinal upset, fatigue or weakness, dizziness or lightheadedness and difficulty sleeping. Each of the five questions is asked with the corresponding 0 to 3 rating of the response (0 = Not present, 1 = mild, 2 = moderate, 3 = severe). The sum of the responses on these questions is then calculated, resulting in the AMS severity.

    Measured: Day 1 to 3 at 3'100m

  2. Acute mountain sickness (AMS) at 760 m with and without acetazolamide, severity

    Difference between acetazolamide and placebo group in the severity of AMS at 760 m.

    Measured: Day 3 at 760 m

  3. Altitude related adverse health effects (ARAHE), incidence

    Difference between acetazolamide and placebo group in the incidence of ARAHE during the stay at 3'100 m.

    ARAHE are defined as the following:

    • Moderate to severe AMS (Lake Louise score ≥3 and/or Environmental Symptoms questionnaire AMSc score ≥0.7) and/or any of the following:
    • Severe hypoxemia (SpO2 at rest <80% for >30 min or <75% for >15 min, exercise oxygen desaturation SpO2 <75% for >1 min accompanied by symptoms or signs of hypoxemia)
    • Symptomatic cardiovascular disease (arterial blood pressure systolic >200 mmHg, diastolic >110 mmHg not responding to blood pressure lowering drugs within 1 hr; chest pain with ECG signs of ischemia or new onset arrhythmia)
    • Withdrawal from the study by the decision of the independent physician for safety reasons or by the patient.

    Measured: Day 1 to 3 at 3'100m

  4. Spirometric measurement of forced expiratory volume in one second

    Difference in altitude-induced change in the forced expiratory volume in one second between the acetazolamide and placebo group

    Measured: Day 2 at 760m and day 2 at 3'100m

  5. Arterial partical pressure of oxygen

    Difference in altitude-induced changes in arterial partical pressure of oxygen between the acetazolamide and placebo group

    Measured: Day 2 at 760m and day 2 at 3'100m

  6. Drug side effects

    Difference between acetazolamide and placebo group in the incidence of medication side effects during the stay at 3'100 m.

    Measured: Day 1 to 3 at 3'100m

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted19 Jun 2018
  2. Study start15 May 2018
  3. Primary completion31 Aug 2019
  4. Study completion31 Aug 2019

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 4
Primary purpose
Prevention
Allocation
Randomised
Intervention model
Parallel groups
Masking
Quadruple blind
Who is masked
Participant, Care provider, Investigator, Outcomes assessor
Enrolment
349 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT03561675
Sponsor's protocol ID
2018-01-8/305
Status last verified
May 2021
First submitted
14 May 2018
Last updated
13 May 2021
Results posted
No
Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No

Publications

  • Hafliger A, Buergin A, Mayer LC, Mademilov M, Lichtblau M, Sooronbaev T, Ulrich S, Bloch KE, Furian M. Sex-Specific Difference in Health-Related Altitude-Effects and Their Prevention by Acetazolamide. Data from a Randomized Controlled Trial. High Alt Med Biol. 2025 Jun;26(2):195-203. doi: 10.1089/ham.2024.0011. Epub 2025 Jan 8.

    PubMed 39778901

  • Furian M, Mademilov M, Buergin A, Scheiwiller PM, Mayer L, Schneider S, Emilov B, Lichtblau M, Bitos K, Muralt L, Groth A, Reiser AE, Sevik A, Sheraliev U, Marazhapov NH, Aydaralieva S, Muratbekova A, Tabyshova A, Abdraeva A, Buenzli S, Sooronbaev TM, Ulrich S, Bloch KE. Acetazolamide to Prevent Adverse Altitude Effects in COPD and Healthy Adults. NEJM Evid. 2022 Jan;1(1):EVIDoa2100006. doi: 10.1056/EVIDoa2100006. Epub 2021 Dec 22.

    PubMed 38296630

  • Graf LC, Furian M, Bitos K, Mademilov M, Abdraeva A, Buenzli J, Buenzli S, Aidaralieva S, Sheraliev U, Mayer LC, Schneider SR, Sooronbaev TM, Ulrich S, Bloch KE. Effect of altitude and acetazolamide on sleep and nocturnal breathing in healthy lowlanders 40 y of age or older. Data from a randomized trial. Sleep. 2023 Apr 12;46(4):zsac269. doi: 10.1093/sleep/zsac269.

    PubMed 36356042

Questions about this trial

What is this clinical trial studying?

A Phase 4 study testing ACETAZOLAMIDE oral capsule in people with Acute Mountain Sickness, run by University of Zurich at 1 site in Kyrgyzstan.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 4 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 13 May 2021. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in Kyrgyzstan. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Acute mountain sickness (AMS), incidence (time frame: Day 1 to 3 at 3'100m). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT03561675, which also lists 3 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 13 May 2021.

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