A Phase 4 interventional study of Acetazolamide and Methazolamide in Altitude Sickness and Hypertension, Pulmonary, sponsored by University of British Columbia. Completed at 1 site in Canada. Open to male participants aged 18 Years to 40 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2016-10-19.
Sponsored by University of British Columbia · Phase 4, Interventional, and Basic science
The purpose of this proposal is to compare the physiological effects of acetazolamide (AZ) and methazolamide (MZ) on the control of breathing and hypoxic pulmonary vasoconstriction. The first objective is to assess the effects of AZ and MZ on the control of breathing in normoxia and hypoxia. To achieve this the ventilatory interaction between oxygen and carbon dioxide will be measured and effects compared between placebo, AZ, and MZ conditions. In addition, the isocapnic and poikilocapnic hypoxic ventilatory response and hypercapnic ventilatory response will be measured with each drug. The second objective is to assess the effects of AZ and MZ on the control of the pulmonary vasculature during hypoxia. Pulmonary pressure and cardiac output will be measured during 60 minutes of poikilocapnic hypoxia.
1,105 studies on the registry are indexed under Hypertension, Pulmonary; 234 are open to participants now.
This study's enrollment of 14 is below the median of 35 across 649 interventional studies indexed under Hypertension, Pulmonary.
Browse Hypertension, Pulmonary studies →University of British Columbia is the lead sponsor of 1,309 studies on the registry; 253 are open to participants now.
Of its 6 completed or terminated interventional studies of FDA-regulated products, 1 (17%) have results posted.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
Participants will be dosed 250mg Acetazolamide (p.o.) three times per day for two days prior to and a single dose on the day of study.
Drug: Acetazolamide
Participants will be dosed 100mg Methazolamide (p.o.) twice daily separated by a placebo for two days prior to and a single dose on the day of study. The placebo dose is provided to match the dosing schedule between conditions.
Drug: Methazolamide
Participants will take (p.o.) placebo pills three times per day for two days prior to and a single dose on the day of study.
Drug: Placebo
Change in ventilation
To quantify the isocapnic hypoxic ventilatory response, the hypercapnic ventilatory response, and the hypercapnic hypoxic ventilatory response, ventilation will be measured throughout controlled changes in end-tidal gas levels. Each protocol will consist of 90s steps in end-tidal oxygen partial pressure from baseline through 65, 57, and 47 mmHg. For hypercapnic hypoxia, the end-tidal partial pressure for carbon dioxide will be increased from baseline to +6 mmHg for 7 minutes before reducing the end-tidal partial pressure of oxygen as above. The poikilocapnic hypoxic ventilatory response will be determined by measuring the change in ventilation from baseline throughout 60 minutes of poikilocapnic hypoxia (fraction of inspired oxygen = 0.12)
Time frame: Baseline and 60 minutes of poikilocapnic hypoxia
Change in pulmonary artery pressure
Pulmonary artery systolic pressure (PASP) will be derived using the modified Bernoulli equation and the regurgitant velocity across the tricuspid valve. Estimates of right atrial pressure will be evaluated based upon the collapsibility index of the inferior vena cave during a sniff test. The pulmonary artery pressure response will be measured during 60 minutes of exposure to poikilocapnic hypoxia (fraction of inspired oxygen = 0.12)
Time frame: Baseline and 60 minutes of poikilocapnic hypoxia
Change in cerebral blood velocity
To quantify the isocapnic hypoxic cerebral blood velocity response, the hypercapnic cerebral blood velocity response, and the hypercapnic hypoxic cerebral blood velocity response, cerebral blood velocity in the middle and posterior cerebral arteries will be measured throughout controlled changes in end-tidal gas levels. Each protocol will consist of 90s steps in end-tidal oxygen partial pressure from baseline through 65, 57, and 47 mmHg. For hypercapnic hypoxia, the end-tidal carbon dioxide partial pressure will be increased from baseline to +6 mmHg for 7 minutes before reducing the end-tidal oxygen partial pressure as above. The poikilocapnic hypoxic ventilatory response will be determined by measuring the change in ventilation from baseline throughout 60 minutes of poikilocapnic hypoxia (fraction of inspired oxygen = 0.12)
Time frame: Baseline and 60 minutes
change in arterial oxygen partial pressure
Time frame: Baseline and 60 minutes
Change in arterial carbon dioxide partial pressure
Time frame: Baseline and 60 minutes
Change in arterial pH
Time frame: Baseline and 60 minutes
Change in heart rate
Time frame: Baseline and 60 minutes
change in blood pressure
Time frame: Baseline and 60 minutes
change in end-tidal oxygen and carbon dioxide partial pressure
Time frame: Baseline and 60 minutes
Change in arterial oxygen saturation
Time frame: Baseline and 60 minutes
Change in cardiac output
Cardiac output will be determined using the aortic time integral velocity and the diameter of the aortic valve annulus. Data will be collected at baseline and throughout exposure to poikilocapnic hypoxia (fraction of inspired oxygen = 0.12)
Time frame: Baseline and 60 minutes of poikilocapnic hypoxia
Change in pulmonary venous blood velocity
Doppler ultrasound will be used to measure the velocity of blood draining from the pulmonary vein at baseline and throughout exposure to poikilocapnic hypoxia (fraction of inspired oxygen = 0.12)
Time frame: Baseline and 60 minutes of poikilocapnic hypoxia
Hemoglobin
Time frame: Baseline
albumin
Time frame: Baseline
iron
Time frame: Baseline
This study is completed, as verified in Oct 2016. You cannot join it, but the record below documents what was studied.
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University of British Columbia