Abstract Introduction Obstructive sleep apnea (OSA) is a common pathology, having a prevalence of 6% among women and 13% of men. Adherence rates to positive airway pressure (PAP) therapy are suboptimal, with only 65% to 80% of patients continuing use after four years. Compliance rates of PAP therapy are affected by pressure settings, interfaces, claustrophobia and patient misperception. Alternative therapies include hypoglossal nerve stimulation, EPAP devices and oral appliances. Recent studies have expanded on the usage of acetazolamide’s role in treating OSA. This case illustrates both efficacy and tolerability of acetazolamide’s therapeutic effect in a veteran with severe OSA. Case Report A 64-year-old male with a past medical history of hypertension presented to the sleep clinic with a diagnosis of severe OSA, nonadherent to both CPAP and oral appliance therapy. The patient’s initial in-lab polysomnogram (2015) illustrated an AHI of 50 events/hour, sleep efficiency of 77%, Total Arousal Index of 55 events/hour, supine AHI of 117, and non-supine AHI of 19. In NREM sleep, the patient exhibited a mean oxygen saturation of 92%. Veteran was intolerant to auto-CPAP therapy secondary to claustrophobia; oral appliance therapy demonstrated partial efficacy, reducing his AHI to 20. Veteran was lost to follow up and reevaluated in December 2023; given his weight loss of 41 pounds a home sleep study was ordered to confirm the severity of his severe disordered breathing, which showed an AHI of 16. The patient was started on acetazolamide 125 mg nightly. A repeat home sleep study in the context of acetazolamide after 3 weeks demonstrated a decrease of AHI from 16 to 0.9, with snoring decreasing from 10.0% to 1.4%. Discussion Reductions in AHI have been evidenced in various pharmacologic therapies—including agents that increase upper airway muscle tone, ventilatory drive, or arousal threshold. Examples include norepinephrine reuptake inhibitors (e.g., atomoxetine), antimuscarinics (e.g., oxybutynin), and cannabinoid receptor agonists (e.g., dronabinol), among others. Acetazolamide has been shown to reduce the number of respiratory events per hour. As a carbonic anhydrase inhibitor, it produces metabolic acidosis that increases ventilatory drive. OSA has been associated with increased carbonic anhydrase activity, and carbonic anhydrase inhibitors such as acetazolamide may lower vascular tone through several pathways. Further research is needed to confirm whether acetazolamide’s effect is longitudinal and to identify which OSA patient phenotypes are responsive to acetazolamide. For individuals who do not tolerate standard therapies, such as CPAP, acetazolamide monotherapy may be an efficacious treatment option. This abstract is funded by: None
Das et al. (2026) studied this question.