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Study identifier: NCT07118462 Synced from ClinicalTrials.gov · July 29, 2026
● Recruiting

HighCycle Study: Acetazolamide, High Altitude and Plasma Volume

Condition: High Altitude Effects · High Altitude Hypoxia · Acute Mountain Sickness (AMS)  ·  Sponsor: Centre d'Expertise sur l'Altitude EXALT

PhasePhase 4
Planned participants270
Who can joinAll sexes, 18 Years to 44 Years
Healthy volunteersYes

About this study

Each year, millions of people living at low altitude (\< 1,000 m) travel to high altitude (≥ 2,500 m) for work, tourism, or sports activities. These individuals are exposed to hypobaric hypoxia, which can trigger acute mountain sickness (AMS)-the most common form of altitude-related illness. Therefore, understanding the physiological responses to hypoxia that allow acclimatization, as well as the pathophysiology of acute mountain sickness, is of primary importance. The hematological response to high-altitude exposure initially includes a reduction in plasma volume (PV), leading to an early increase in hemoglobin concentration within the first 24 hours. In contrast, an increase in hemoglobin mass requires several weeks at high altitude. Recent well-controlled physiological studies conducted in hypobaric chambers have demonstrated that this hypoxia-induced PV contraction results from fluid redistribution from the intravascular to the extravascular compartment, rather than from water loss due to increased diuresis. Prophylaxis of AMS is primarily based on the administration of 250 mg/day of acetazolamide (ACZ), a carbonic anhydrase inhibitor with a mild diuretic effect. Acetazolamide induces metabolic acidosis, which stimulates ventilation and thereby improves oxygenation. The effect of prophylactic ACZ use during high-altitude exposure on PV in lowlanders remains unknown: it is unclear whether ACZ leads to a greater reduction in PV due to its diuretic effect, or to a smaller …

This description comes directly from the study's public registry record.

Talk to the study team

Benoit Champigneulle, MD PhD  ·  +33476769288  ·  BChampigneulle@chu-grenoble.fr

Paul Robach, PhD  ·  +33667053919  ·  paul.robach@ensm.sports.gouv.fr

Always discuss trial participation with your own doctor first.

Locations (1)

National Center for Cardiology and Internal MedicineBishkek, KyrgyzstanRecruiting

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Source record: clinicaltrials.gov/study/NCT07118462