HighCycle Study: Effect of Acetazolamide on Plasma Volume During Acute Exposure to High Altitude in Women and Men

What this Trial Is About

Millions of people who normally live at low altitudes travel to high altitudes for work, tourism, or sports, exposing themselves to low oxygen levels that can cause acute mountain sickness (AMS), a common altitude-related illness. This study focuses on understanding how the body adjusts to low oxygen by examining changes in blood plasma volume and how acetazolamide, a drug used to prevent AMS, affects these changes during rapid ascent to high altitude. Participants will receive either acetazolamide capsules (250 mg per day, split into two doses) or placebo capsules that look identical. The medication begins 24 hours before ascending to 3600 meters and continues until the morning after spending two nights at that altitude. The study compares plasma volume changes in people taking acetazolamide versus placebo during this acute high-altitude exposure. During the study, plasma volume will be measured on the first day at low altitude (760 m) and on the second and third days at high altitude (3600 m). Researchers will also assess differences related to sex, AMS symptoms, hormone levels, and arterial blood gases. The trial includes healthy men and women aged 18 to 44 years who live at low altitude, with monitoring before, during, and after the high-altitude exposure to understand physiological responses and treatment effects.

HighCycle Study: Acetazolamide, High Altitude and Plasma Volume