Effect of acetazolamide on 24-hour blood pressure in highlanders with obstructive sleep apnea: a randomized, placebo-controlled, double-blinded

<bold>Background and Aims:</bold> Acetazolamide (Acz) is effective in reducing blood pressure in obstructive sleep apnea (OSA) patients living at low and those ascending to high altitudes. However, its impact on 24-hour blood pressure in highlanders with OSA remains unclear. <bold>Methods:</bold> In a randomized, placebo-controlled, double-blind crossover trial, forty-one patients with moderate to severe OSA living in Lhasa (3650m) were randomly assigned to receive either 500mg/day Acz or placebo for two weeks each, separated by a one-week washout period. At the end of each treatment period, 24-hour ambulatory blood pressure (BP) and clinical examinations were carried out. The primary outcome was the difference in 24-hour mean blood pressure (MAP) between the 2-week Acz and placebo treatment. The trial was pre-registered at the Chinese Clinical Trial Registry (ChiCTR2100049304). <bold>Results:</bold> Of the 41 patients, 35(85.4%) were male, with a mean±SE age of 39.6±0.9years and body mass index of 25.2±0.4kg/m2. With placebo, the mean±SE 24-hour MAP was 86±3mmHg. Acz decreased 24-hour MAP by a mean (95%CI) of 3mmHg (0 to 5). Similar results was found in 24-hour systolic and diastolic BP and heart rate. Multivariable regression analysis showed that baseline apnea-hypopnea index (coefficient -0.15, 95%CI -0.27 to -0.04, p=0.010) was an independent predictor for the Acz-related reduction in 24-hour MAP. Mild to moderate paresthesia in the limbs was the most common side effect. <bold>Conclusions:</bold> In highlanders with OSA, Acz significantly reduced 24-hour blood pressure and heart rate, suggesting that it may be a promising drug to manage blood pressure in highlanders with OSA.