Acetazolamide and Exercise Performance at Altitude

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details. Identifier: NCT03525561
Recruitment Status : Recruiting
First Posted : May 15, 2018
Last Update Posted : October 15, 2018
Information provided by (Responsible Party):
United States Army Research Institute of Environmental Medicine

Brief Summary:
The goals of the present study are to evaluate whether the most common, and effective, treatment for acute mountain sickness (AMS), acetazolamide (AZ), has a negative, positive, or no influence on exercise performance, cognitive performance, or manual dexterity in young healthy subjects during simulated altitude exposure. AMS represents a serious challenge to the health and performance of the Warfighter who may need to rapidly deploy to high altitude. However, there have been concerns that AZ might alter or impair endurance exercise performance, and possibly fine motor skills. These would represent major limitations to the use of this drug in a Warfighter who has a specific timeframe in which to accomplish mission tasks. In the present project, we will use exposure to simulated altitude in the USARIEM hypobaric chamber to quantify the impact, if any, of AZ on endurance exercise performance following rapid ascent to 3500 meters (m) in unacclimatized lowlander volunteers. The study will be conducted using a randomized, single-blind, placebo-controlled crossover study design. Ten male and female volunteers will complete one orientation day, one VO2peak day, three days of familiarization testing at sea level (SL), then two rounds of experimental testing. Each round of experimental testing consists of six days including four days to establish baseline euhydration, followed by a 30 hour (hr) exposure to 3500 m. Volunteers will have a two week break between experimental testing rounds for washout of any effects of altitude acclimation. During one experimental round, volunteers will take two doses of AZ each day (Phase 1: 250 mg/dose,500 mg/day, Phase 2: 125 mg/dose, 250 mg/day) starting 48 hr prior to their altitude exposure and continuing for the 30 hr stay at high altitude. During the other experimental condition, volunteers will be given a placebo at the same time points as the doses of AZ. Prior to altitude exposure, AMS will be evaluated and volunteers will then ascend to a simulated altitude of 3500 m, where they will remain for 30 hr. Volunteers will rest at altitude for an hr, after which they will complete an AMS questionnaire, resting ventilation measurements, provide a blood sample and complete cognitive and finger dexterity testing. Subjects will then perform 15 minutes (min) of steady state (SS) treadmill exercise at 40-45% of SL VO2peak and a 2 mile treadmill time trial (TT). Volunteers will stay overnight in the hypobaric chamber with research staff supervision. The following morning, metabolic and blood measurements will again be completed, after which volunteers will perform the exercise testing for a second time. Cognitive and finger dexterity testing will be performed before volunteers return to sea level (i.e., "descend" from the simulated altitude). The results of the proposed study will, for the first time, provide quantitative evidence regarding whether AZ treatment impairs endurance exercise performance in the context of a Warfighter-relevant endurance exercise task.

Condition or disease Intervention/treatment Phase
Hypoxia Exercise Performance Cognitive Function Dexterity Drug: Acetazolamide Pill Drug: Placebo pill Early Phase 1

Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 10 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Intervention Model Description: Subjects will serve as their own controls. Will exercise during simulated altitude exposure twice, once with acetazolamide and once with placebo.
Masking: Single (Participant)
Masking Description: Single-blind use of acetazolamide where participant is not informed. Goal is to evaluate effect (or lack thereof) on exercise performance.
Primary Purpose: Basic Science
Official Title: Influences of Acetazolamide on Endurance Exercise Performance and Cognitive Function During Acute Exposure to Hypobaric Hypoxia
Actual Study Start Date : October 10, 2018
Estimated Primary Completion Date : October 2020
Estimated Study Completion Date : October 2020

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
Active Comparator: acetazolamide arm
This is the arm of the study in which the volunteers will take the acetazolamide (Diamox) pill.
Drug: Acetazolamide Pill
Subjects will take acetazolamide pill (Diamox), 500 mg/ day, and assess effect on exercise performance during 30-hour exposure to 3,500 m simulated altitude.
Other Name: Diamox

Placebo Comparator: placebo arm
This is the arm of the study in which volunteers will take the placebo.
Drug: Placebo pill
Subjects will take placebo pill and then we will assess exercise performance during 30-hour exposure to 3,500 m simulated altitude.

Primary Outcome Measures :
  1. Endurance exercise performance [ Time Frame: Exercise performance will be assessed during a 30-hour simulated altitude exposure, once during placebo and once during acetazolamide administration ]
    the primary outcome measure is performance of a 2-mile treadmill time trial (self-paced) at simulated altitude.

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 45 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

Volunteers must meet all of the following criteria to be included in the study:

  • Male or female, age 18-45
  • In good health as determined by Office of Medical Support and Oversight (OMSO) General Medical Clearance
  • Passed his/her most recent Army Physical Fitness Test (APFT; military volunteers only) or exercise at least 2 times per week (civilian volunteers)
  • Willing to not exercise, drink alcoholic beverages, or consume caffeinated products for 24 hours before each testing session.
  • Willing not to consume carbonated beverages during the experimental phases of the study (this does not include the two week break between experimental phases)
  • Willing to stay and sleep in an altitude chamber (the size of a dorm room) ~60 hours total (two ~30 hr exposures).
  • Body mass index (BMI) ≤ 28.5

Exclusion Criteria:

  • Females who are pregnant or planning to become pregnant during the study
  • Taking dietary supplements, prescriptions, or over the counter medication, other than a contraceptive (unless approved by OMSO and PI)
  • Born at altitudes greater than 2,100 m (~7,000 feet; Examples include Santa Fe, New Mexico; Laramie, Wyoming; Etc.)
  • Living in areas that are more than 1,200 m (~4,000 feet), or have traveled to areas more than 1,200 m for five days or more within the last 2 months (Examples include Ft. Huachuca, Arizona; Lima, Peru; Feldberg, Germany; etc.)
  • Physical problems/injuries associated with walking or running on a treadmill
  • Allergy to skin adhesive
  • Abnormal blood count (For example: hemoglobin (Hb) outside of the normal ranges (Normal [Hb] Males = 12.6-17.7 g/dL; Females = 11.1-15.9 g/dL) or hematocrit (Hct) outside of the normal ranges (Normal Hct Males = 37.5-51.0%; Females = 34.0-46.6%) levels, presence of abnormal blood chemicals (hemoglobin S or sickle cell traits)
  • Prior HAPE (high altitude pulmonary edema) or HACE (high altitude cerebral edema) diagnosis
  • Smokers or tobacco/nicotine users (unless have quit more than 4 months prior)
  • Presence of asthma or respiratory tract infections (unless more than 1 month prior or approved by OMSO).
  • Allergy to sulfa drugs (Acetazolamide)
  • Evidence of apnea or other sleeping disorders
  • History of neurologic (e.g. stroke, seizure), speech, facial muscle disorder or injuries preventing from producing normal range of hand and finger motion
  • Experiencing colds, coughs, or sinus infections
  • Food allergies/intolerances to gluten and/or dairy
  • Low blood Na+/K+ values ( Na+: < 135 mmol/L, K+: <3.5 mmol/L)
  • Kidney, liver or adrenal dysfunction
  • Breastfeeding mothers

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT03525561

Contact: Robert Roussel, Ph.D. 508-233-6306
Contact: Karleigh Bradbury, M.S. 508-233-4977

United States, Massachusetts
Natick Soldier Systems Center Recruiting
Natick, Massachusetts, United States, 01760
Contact: Robert R Roussel, PhD         
Principal Investigator: Nisha Charkoudian, PhD         
Sponsors and Collaborators
United States Army Research Institute of Environmental Medicine
Principal Investigator: Nisha Charkoudian, Ph.D. United States Army Research Institute of Environmental Medicine

Responsible Party: United States Army Research Institute of Environmental Medicine Identifier: NCT03525561     History of Changes
Other Study ID Numbers: M-10729
First Posted: May 15, 2018    Key Record Dates
Last Update Posted: October 15, 2018
Last Verified: October 2018
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: Undecided

Studies a U.S. FDA-regulated Drug Product: Yes
Studies a U.S. FDA-regulated Device Product: No
Product Manufactured in and Exported from the U.S.: No

Additional relevant MeSH terms:
Signs and Symptoms, Respiratory
Signs and Symptoms
Carbonic Anhydrase Inhibitors
Enzyme Inhibitors
Molecular Mechanisms of Pharmacological Action
Natriuretic Agents
Physiological Effects of Drugs