Millions of people travel to high altitude for work or leisure activities and are exposed to reduced inspiratory oxygen partial pressure and hypoxemia that may lead to altitude illness, among which the most common form is acute mountain sickness (AMS). The main AMS symptoms are headache, malaise, weakness, and fatigue. Prospective studies have shown that 20-60% of newcomers at 2500-4000m develop AMS requiring them to take medications, while, at very high altitudes, AMS may progress to high altitude cerebral oedema. Whether women are more susceptible to AMS remains insufficiently understood since no prospective study controlled for sex hormones, use of hormone contraception or assessed menstrual cycle phase (MCP) at altitude. Therefore, women remain underrepresented and poorly characterized in high altitude studies. In addition, the efficacy and safety of 250 mg/day acetazolamide, the standard recommendation for AMS prevention, has never been compared between sexes, although, women have presumably higher acetazolamide plasma concentration due to lower blood volume. Given the known dose-dependent preventive but also side effects of acetazolamide and equal proportion of women and men among mountain travellers, there is an urgent need to conclusively quantify the efficacy and safety of pre-ventive acetazolamide therapy against AMS in women compared to men.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
QUADRUPLE
Enrollment
303
Administration of 1x125mg acetazolamide in the morning, 1x125mg in the evening, starting 24 hours before departure to 3600 m.
Administration of equally looking placebo capsules in the morning and in the evening, starting 24 hours before departure to 3600 m.
National Center for Cardiology and Internal Medicine
Bishkek, Gorod Bishkek, Kyrgyzstan
Acute Mountain Sickness (AMS) Incidence, LLS 2018
Sex-related difference between acetazolamide and placebo group in the incidence of AMS. AMS incidence will be defined as a Lake Louise Questionnaire version 2018 score of ≥3.
Time frame: Day 1 to 3 at 3600 m
Acute Mountain Sickness (AMS) Incidence, LLS 1993
Sex-related difference between acetazolamide and placebo group in the incidence of AMS. AMS incidence will be defined as a Lake Louise Questionnaire version 1993 score of ≥3.
Time frame: Day 1 to 3 at 3600 m
Acute Mountain Sickness (AMS) Severity, LLS 2018
Sex-related difference between acetazolamide and placebo group in the AMS severity assessed by the Lake Louise Questionnaire version 2018.
Time frame: Day 1 to 3 at 3600 m
Acute Mountain Sickness (AMS) Severity, LLS 1993
Sex-related difference between acetazolamide and placebo group in the AMS severity assessed by the Lake Louise Questionnaire version 1993.
Time frame: Day 1 to 3 at 3600 m
Drug-related side effects
Sex-related difference between acetazolamide and placebo group in the incidence and severity of medication side effects.
Time frame: Day 1 to 3 at 3600 m
Arterial blood gases
Sex-related differences between acetazolamide and placebo group in the arterial blood gases (pH, PaO2, PaCO2, SaO2).
Time frame: Day 2 at 760 m and day 2 at 3600 m
Acetazolamide plasma concentration
Sex-related differences between acetazolamide plasma concentration assessed by dried blood spots.
Time frame: Day 2 at 3600 m
Hypoxic ventilatory response
Sex-related difference in the hypoxic ventilatory response assessed under FiO2 of 0.115 and while cycling on a bicycle at 30% of predicted maximal work capacity.
Time frame: Day 2 at 760 m
Perceived pain visualization
Sex-related differences between acetazolamide and placebo group on perceived pain sensations, visualized by the SMaRT tablet app
Time frame: Day 1 to 3 at 3600 m
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