High AltitudePhase 4NCT06498505
HighCycle: Effect of Acetazolamide on Pulmonary Artery Pressure in Women Compared to Men
A Phase 4 study testing Acetazolamide in people with High Altitude, run by University of Zurich at 1 site in Kyrgyzstan.
Trial summary
Randomized clinical trial evaluating the effect of acetazolamide on pulmonary artery pressure in women compared to men travelling to 3600 m. Read more about this study
- Who is it for?
- Ages 18 to 44 yearsHealthy volunteers can take part
- Conditions the study is for
- High Altitude
- What is being tested?
- Acetazolamide
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 303 participants
- Where
- 1 siteKyrgyzstan
- Study dates
- 15 Jul 2024to 31 Aug 2025
- 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 18 to 44 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Healthy, non-smoking men and women, age 18-44 years, without any diseases and need of regular medication (including oral contraceptives).
- BMI >18 kg/m2 and <30 kg/m2
- Born, raised and currently living at altitudes <1000 m
- Written informed consent
- Premenopausal women with an eumenorrheic cycle
Who cannot join
- Other types of contraceptvies (hormonal intrauterine device, vaginal ring, subcutaneous injections or implants, among others)
- Pregnancy or nursing
- Anaemic (haemoglobin concentration <10g/dl)
- Any altitude trip <4 weks before the study
- Allergy to acetazolamide and other sulfonamides
Trial locations and contacts
1 site in 1 country.
Kyrgyzstan1 site
National Center for Cardiology and Internal Medicine
Bishkek, Bishkek, 720040
About this study
Official title: HighCycle: Effect of Acetazolamide on Pulmonary Artery Pressure in Women Compared to Men. A Randomized, Placebo-Controlled, Double-Blind Parallel Trial.
Randomized clinical trial evaluating the effect of acetazolamide on pulmonary artery pressure in women compared to men travelling to 3600 m.
- Conditions
- High Altitude
- Being tested
- Acetazolamide, Placebo
- Keywords
- Women, Hypoxia, Prevention, Acetazolamide, Echocardiography
- Medical subject headings
- Altitude Sickness, Hypoxia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
AcetazolamideDrug
Administration of 1x125mg acetazolamide in the morning, 1x125mg in the evening, starting 24 hours before departure to 3600 m.
PlaceboDrug
Administration of equally looking placebo capsules in the morning and in the evening, starting 24 hours before departure to 3600 m.
| Study group | Role | What they receive |
|---|---|---|
| WOMEN - ACETAZOLAMIDE oral capsule | Active comparator | Acetazolamide 250 mg/day (capsules @125 mg; 1 in the morning, 1 in the evening), orally. Medication starts 24 hours before ascent to 3600 m until the morning after the second night at 3600 m Receives: Drug: Acetazolamide |
| MEN - ACETAZOLAMIDE oral capsule | Active comparator | Acetazolamide 250 mg/day (capsules @125 mg; 1 in the morning, 1 in the evening), orally. Medication starts 24 hours before ascent to 3600 m until the morning after the second night at 3600 m Receives: Drug: Acetazolamide |
| WOMEN - PLACEBO oral capsule | Placebo comparator | Placebo (capsules identically looking as acetazolamide capsules; 1 in the morning, 1 in the evening), orally. Medication starts 24 hours before ascent to 3600 m until the morning after the second night at 3600 m. Receives: Drug: Placebo |
| MEN - PLACEBO oral capsule | Placebo comparator | Placebo (capsules identically looking as acetazolamide capsules; 1 in the morning, 1 in the evening), orally. Medication starts 24 hours before ascent to 3600 m until the morning after the second night at 3600 m. Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Pulmonary artery Pressure (PAP)
Sex-related difference in the altitude-induced change in RV/RA in mmHg assessed by echocardiography between acetazolamide and placebo group.
Measured: Day 2 at 760 m and Day 2 at 3600 m
Secondary outcomes (2)
Lung comets
Sex-related difference in the altitude-induced change in ultrasound lung comets assessed by echocardiography between acetazolamide and placebo group.
Measured: Day 2 at 760 m and Day 2 at 3600 m
Parameters of right heart function
Sex-related difference in the altitude-induced change in parameters of right heart function assessed by echocardiography between acetazolamide and placebo group.
Measured: Day 2 at 760 m and Day 2 at 3600 m
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 Jul 2024
- Study start15 Jul 2024
- Primary completion31 Aug 2025
- Study completion31 Aug 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for High AltitudeStudies 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
- 303 participants (actual)
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, University Hospital Heidelberg, Laboratoire des Adaptations Métaboliques à l'Exercice en conditions Physiologiques et Pathologiques
- Responsible party
- Sponsor
- Investigators
- Silvia Ulrich, Prof. Dr., Study chair, University of ZurichTalant Sooronbaev, Prof. Dr., Study director, National Center of Cardiology and Internal Medicine, Bishkek, Kyrgyzstan
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06498505
- Sponsor's protocol ID
- HighCycle_PAP
- Status last verified
- Jun 2026
- First submitted
- 5 Jul 2024
- Last updated
- 5 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 5 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- HighCycle: Effect of Acetazolamide on Pulmonary Artery Pressure in Women Compared to Men. A Randomized, Placebo-Controlled, Double-Blind Parallel Trial.
- ClinicalTrials.gov ID
- NCT06498505
- Acronym / sponsor ID
- HighCycle_PAP
- Conditions
- High Altitude
- Keywords
- Women, Hypoxia, Prevention, Acetazolamide, Echocardiography
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 303 participants (actual)
- Lead sponsor
- University of ZurichUniversity, hospital or other
- Collaborators
- National Center of Cardiology and Internal Medicine named after academician M.Mirrakhimov, University Hospital Heidelberg, Laboratoire des Adaptations Métaboliques à l'Exercice en conditions Physiologiques et Pathologiques
- Study start
- 15 Jul 2024 (actual)
- Primary completion
- 31 Aug 2025 (actual)
- Study completion
- 31 Aug 2025 (actual)
- First posted
- 12 Jul 2024 (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 clinical trial evaluating the effect of acetazolamide on pulmonary artery pressure in women compared to men travelling to 3600 m.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| WOMEN - ACETAZOLAMIDE oral capsule | Active comparator | Drug: AcetazolamideAcetazolamide 250 mg/day (capsules @125 mg; 1 in the morning, 1 in the evening), orally. Medication starts 24 hours before ascent to 3600 m until the morning after the second night at 3600 m |
| MEN - ACETAZOLAMIDE oral capsule | Active comparator | Drug: AcetazolamideAcetazolamide 250 mg/day (capsules @125 mg; 1 in the morning, 1 in the evening), orally. Medication starts 24 hours before ascent to 3600 m until the morning after the second night at 3600 m |
| WOMEN - PLACEBO oral capsule | Placebo comparator | Drug: PlaceboPlacebo (capsules identically looking as acetazolamide capsules; 1 in the morning, 1 in the evening), orally. Medication starts 24 hours before ascent to 3600 m until the morning after the second night at 3600 m. |
| MEN - PLACEBO oral capsule | Placebo comparator | Drug: PlaceboPlacebo (capsules identically looking as acetazolamide capsules; 1 in the morning, 1 in the evening), orally. Medication starts 24 hours before ascent to 3600 m until the morning after the second night at 3600 m. |
Who may qualify
- Ages
- 18 to 44 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Healthy, non-smoking men and women, age 18-44 years, without any diseases and need of regular medication (including oral contraceptives).
- BMI >18 kg/m2 and <30 kg/m2
- Born, raised and currently living at altitudes <1000 m
- Written informed consent
- Premenopausal women with an eumenorrheic cycle
Key exclusion criteria (5 listed)
- Other types of contraceptvies (hormonal intrauterine device, vaginal ring, subcutaneous injections or implants, among others)
- Pregnancy or nursing
- Anaemic (haemoglobin concentration <10g/dl)
- Any altitude trip <4 weks before the study
- 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 |
|---|---|---|
| AcetazolamideAdministration of 1x125mg acetazolamide in the morning, 1x125mg in the evening, starting 24 hours before departure to 3600 m. | Drug | MEN - ACETAZOLAMIDE oral capsule, WOMEN - ACETAZOLAMIDE oral capsule |
| PlaceboAdministration of equally looking placebo capsules in the morning and in the evening, starting 24 hours before departure to 3600 m. | Drug | MEN - PLACEBO oral capsule, WOMEN - PLACEBO oral capsule |
Primary outcome
Pulmonary artery Pressure (PAP)
Time frame: Day 2 at 760 m and Day 2 at 3600 m
Sex-related difference in the altitude-induced change in RV/RA in mmHg assessed by echocardiography between acetazolamide and placebo group.
2 secondary outcomes
Lung comets
Time frame: Day 2 at 760 m and Day 2 at 3600 m
Parameters of right heart function
Time frame: Day 2 at 760 m and Day 2 at 3600 m
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 5 Jun 2026.
- Individual participant dataSharing planned: Undecided
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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.
Silvia Ulrich, Prof. Dr. study chair
University of Zurich
Talant Sooronbaev, Prof. Dr. study director
National Center of Cardiology and Internal Medicine, Bishkek, Kyrgyzstan
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 in people with High Altitude, 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 5 inclusion and 5 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 5 Jun 2026. 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?
Pulmonary artery Pressure (PAP) (time frame: Day 2 at 760 m and Day 2 at 3600 m). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 5 Jun 2026.