Altitude HypoxiaPhase 4NCT03540914
Effect of Acetazolamide on Right Heart Function at Rest in Lowlanders Older Than 40 Years at Altitude.
A Phase 4 study testing ACETAZOLAMIDE oral capsule in people with Altitude Hypoxia, run by University of Zurich at 1 site in Kyrgyzstan.
Trial summary
Randomized, placebo controlled trial evaluating efficacy of acetazolamide on right heart function at rest 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
- Altitude Hypoxia
- 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
- 400 participants
- Where
- 1 siteKyrgyzstan
- Study dates
- 1 Jun 2018to 31 Dec 2024
- 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
About this study
Official title: Effect of Acetazolamide on Right Heart Function at Rest in Lowlanders Older Than 40 Years at Altitude.: A Randomized, Placebo-controlled, Double-blind Parallel Trial
Randomized, placebo controlled trial evaluating efficacy of acetazolamide on right heart function at rest 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 preventive acetazolamide intake on right heart function at rest 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 200 participants will have completed the study and/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.
- Conditions
- Altitude Hypoxia
- Being tested
- ACETAZOLAMIDE oral capsule, Placebo oral capsule
- Keywords
- healthy participants older than 40 years, right heart function, 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 group | Role | What they receive |
|---|---|---|
| ACETAZOLAMIDE oral capsule | Active comparator | 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 Receives: Drug: ACETAZOLAMIDE oral capsule |
| PLACEBO oral capsule | Placebo comparator | Placebo (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.
Difference in change of pulmonary artery pressure evaluated by echocardiography from 760 m baseline measurement to measurement at 3100 m in the acetazolamide compared to the placebo group
Difference in change of pulmonary artery pressure evaluated by echocardiography from 760 m baseline measurement to measurement at 3100 m between acetazolamide and placebo groups
Measured: Day 2 at 760m and 3100m
Secondary outcomes (11)
Difference in pulmonary artery pressure evaluated by echocardiography at 3100 m in the acetazolamide compared to the placebo group
Difference in pulmonary artery pressure evaluated by echocardiography at 3100 m in the acetazolamide compared to the placebo group
Measured: Day 2 at 3100m
cardiac output
Difference in altitude-induced change of cardiac output between acetazolamide and placebo group, measured by transthoracic echocardiography
Measured: Day 2 at 760m and 3100m
cardiac output
Difference at altitude between acetazolamide and placebo group in cardiac output, measured by transthoracic echocardiography
Measured: Day 2 at 3100m
right heart dimensions
Difference in altitude-induced change of right heart dimensions between acetazolamide and placebo group, measured by transthoracic echocardiography
Measured: Day 2 at 760m and 3100m
right heart dimensions
Difference at altitude of right heart dimensions between acetazolamide and placebo group, measured by transthoracic echocardiography
Measured: Day 2 at 3100m
right heart function
Difference in altitude-induced change of right heart function between acetazolamide and placebo group, measured by transthoracic echocardiography (TAPSE)
Measured: Day 2 at 760m and 3100m
right heart function
Difference at altitude of right heart function between acetazolamide and placebo group, measured by transthoracic echocardiography (TAPSE)
Measured: Day 2 at 3100m
stroke volume
Difference in altitude-induced change of stroke volume between acetazolamide and placebo group, measured by transthoracic echocardiography
Measured: Day 2 at 760m and 3100m
stroke volume
Difference at altitude between acetazolamide and placebo group in stroke volume, measured by transthoracic echocardiography
Measured: Day 2 at 3100m
volumes
Difference in altitude-induced change of volumes between acetazolamide and placebo group, measured by transthoracic echocardiography
Measured: Day 2 at 760m and 3100m
volumes
Difference at altitude of volumes between acetazolamide and placebo group, measured by transthoracic echocardiography
Measured: Day 2 at 3100m
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted30 May 2018
- Study start1 Jun 2018
- Primary completion31 Dec 2024 (estimated)
- Study completion31 Dec 2024 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Altitude HypoxiaStudies of the same condition, open and under way.
- More trials run by University of ZurichThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
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
- 400 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Zurich
- Sponsor type
- University, hospital or other
- Collaborators
- National Center of Cardiology and Internal Medicine named after academician M.Mirrakhimov
- Responsible party
- Sponsor
- Investigators
- Konrad E Bloch, MD, Study chair, University Hospital, ZürichTalant M Sooronbaev,, MD, Study director, National Center of Cardiology and Internal Medicine, Bishkek, KyrgyzstanMichael Furian, MSc, Principal investigator, University Hospital, ZürichSilvia Ulrich, MD, Principal investigator, University Hospital, Zürich
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03540914
- Sponsor's protocol ID
- 2018-01-8/305E
- Status last verified
- Mar 2023
- First submitted
- 15 May 2018
- Last updated
- 10 Mar 2023
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Publications
Mayer L, Lichtblau M, Furian M, Buergin A, Saxer S, Mademilov M, Bader PR, Schneider SR, Sooronbaev T, Bloch KE, Ulrich S. Effect of Acetazolamide on Pulmonary Hemodynamics and Right Heart Function in Healthy Adults Going to Altitude: A Randomized Controlled Trial. J Am Heart Assoc. 2025 Sep 2;14(17):e041941. doi: 10.1161/JAHA.125.041941. Epub 2025 Aug 29.
PubMed 40878988
Study at a glance
From the registry record, last updated by the sponsor on 10 Mar 2023. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effect of Acetazolamide on Right Heart Function at Rest in Lowlanders Older Than 40 Years at Altitude.: A Randomized, Placebo-controlled, Double-blind Parallel Trial
- ClinicalTrials.gov ID
- NCT03540914
- Acronym / sponsor ID
- 2018-01-8/305E
- Conditions
- Altitude Hypoxia
- Keywords
- healthy participants older than 40 years, right heart function, prevention, acetazolamide
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- Unknown status
- Enrolment
- 400 participants (estimated)
- Lead sponsor
- University of ZurichUniversity, hospital or other
- Collaborators
- National Center of Cardiology and Internal Medicine named after academician M.Mirrakhimov
- Study start
- 1 Jun 2018 (actual)
- Primary completion
- 31 Dec 2024 (estimated)
- Study completion
- 31 Dec 2024 (estimated)
- First posted
- 30 May 2018 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Randomized, placebo controlled trial evaluating efficacy of acetazolamide on right heart function at rest 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 preventive acetazolamide intake on right heart function at rest 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 200 participants will have completed the study and/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 design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| ACETAZOLAMIDE oral capsule | Active comparator | Drug: ACETAZOLAMIDE oral capsuleAcetazolamide 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 |
| PLACEBO oral capsule | Placebo comparator | Drug: Placebo oral capsulePlacebo (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. |
Who may qualify
- Ages
- 40 to 75 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- 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
Key exclusion criteria (3 listed)
- 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.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| ACETAZOLAMIDE oral capsuleAdministration of 1x125mg acetazolamide in the morning, 2x125mg in the evening, starting 24 hours before departure to 3'100m | Drug | ACETAZOLAMIDE oral capsule |
| Placebo oral capsuleAdministration of equally looking placebo capsules in the morning and evening, starting 24 hours before departure to 3'100m | Drug | PLACEBO oral capsule |
Primary outcome
Difference in change of pulmonary artery pressure evaluated by echocardiography from 760 m baseline measurement to measurement at 3100 m in the acetazolamide compared to the placebo group
Time frame: Day 2 at 760m and 3100m
Difference in change of pulmonary artery pressure evaluated by echocardiography from 760 m baseline measurement to measurement at 3100 m between acetazolamide and placebo groups
11 secondary outcomes
Difference in pulmonary artery pressure evaluated by echocardiography at 3100 m in the acetazolamide compared to the placebo group
Time frame: Day 2 at 3100m
cardiac output
Time frame: Day 2 at 760m and 3100m
cardiac output
Time frame: Day 2 at 3100m
right heart dimensions
Time frame: Day 2 at 760m and 3100m
right heart dimensions
Time frame: Day 2 at 3100m
right heart function
Time frame: Day 2 at 760m and 3100m
right heart function
Time frame: Day 2 at 3100m
stroke volume
Time frame: Day 2 at 760m and 3100m
stroke volume
Time frame: Day 2 at 3100m
volumes
Time frame: Day 2 at 760m and 3100m
volumes
Time frame: Day 2 at 3100m
Results and safety
Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 10 Mar 2023.
- Derived from this study: PubMed 40878988Mayer L, Lichtblau M, Furian M, Buergin A, Saxer S, Mademilov M, Bader PR, Schneider SR, Sooronbaev T, Bloch KE, Ulrich S. Effect of Acetazolamide on Pulmonary Hemodynamics and Right Heart Function in Healthy Adults Going to Altitude: A Randomized Controlled Trial. J Am Heart Assoc. 2025 Sep 2;14(17):e041941. doi: 10.1161/JAHA.125.041941. Epub 2025 Aug 29.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Konrad E Bloch, MD study chair
University Hospital, Zürich
Talant M Sooronbaev,, MD study director
National Center of Cardiology and Internal Medicine, Bishkek, Kyrgyzstan
Michael Furian, MSc principal investigator
University Hospital, Zürich
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing ACETAZOLAMIDE oral capsule in people with Altitude Hypoxia, 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: status not confirmed, as of the sponsor's last update on 10 Mar 2023. 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?
Results are not available in the source record.
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?
Difference in change of pulmonary artery pressure evaluated by echocardiography from 760 m baseline measurement to measurement at 3100 m in the acetazolamide compared to the placebo group (time frame: Day 2 at 760m and 3100m). 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 NCT03540914, which also lists 1 linked publication.
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 10 Mar 2023.