Abstract
Background: The carbonic anhydrase inhibitor acetazolamide (AZT) modulates blood pressure (BP) at high altitude and reduces sleep disordered breathing in patients with obstructive sleep apnoea (OSA).
Objectives: We aimed to study the treatment effect of AZT in hypertensive OSA patients and hypothesized that AZT induces a BP reduction superior to that of continuous positive airway pressure (CPAP).
Methods: A randomized, three-way cross-over study in 13 male hypertensive patients with moderate-to-severe OSA (mean±SD, apnoea-hypopnea index [AHI] 40±18 n/h, systolic/diastolic BP 154±13/85±9 mmHg). Antihypertensive medication was washed-out. Patients received AZT (titrated to 250 mg t.i.d), CPAP or the combination for two-week periods. Assessments included polygraphic sleep studies, office BP, radial artery oscillatory tonometry and blood chemistry.
Results: AZT and AZT/CPAP significantly reduced mean arterial BP compared to CPAP (95% CI, -7.1 [-10.7 to -3.5] and -7.2 [-10.9 to -3.5] vs. -0.8 [-5.2 to 3.6] mmHg, p=0.02 and 0.02, respectively). Arterial stiffness was reduced by AZT and AZT/CPAP whereas CPAP had no effect on vascular stiffness. AHI decreased after AZT, CPAP and AZT/CPAP (42±27, 86±20 and 96±3 %, all p<0.01, respectively). The reduction of venous bicarbonate concentration following AZT was linearly correlated with the reduction of AHI (r<2=0.66, p=0.013).
Conclusions: AZT reduced BP, vascular stiffness and sleep disordered breathing in OSA patients with comorbid hypertension. A combined pharmacological carbonic anhydrase inhibition and CPAP therapy may provide benefits on top of AHI reduction in hypertensive OSA patients.
- Copyright ©the authors 2017