The Combination of Atomoxetine and Oxybutynin Greatly Reduces Obstructive Sleep Apnea Severity. A Randomized, Placebo-controlled, Double-Blind Crossover Trial

Rationale: There is currently no effective pharmacological treatment for obstructive sleep apnea (OSA). Recent investigations indicate that drugs with noradrenergic and antimuscarinic effects improve genioglossus muscle activity and upper airway patency during sleep. Objectives: We aimed to determine the effects of the combination of a norepinephrine reuptake inhibitor (atomoxetine) and an antimuscarinic (oxybutynin) on OSA severity (apnea-hypopnea index [AHI]; primary outcome) and genioglossus responsiveness (secondary outcome) in people with OSA. Methods: A total of 20 people completed a randomized, placebo-controlled, double-blind, crossover trial comparing 1 night of 80 mg atomoxetine plus 5 mg oxybutynin (ato-oxy) to placebo administered before sleep. The AHI and genioglossus muscle responsiveness to negative esophageal pressure swings were measured via in-laboratory polysomnography. In a subgroup of nine patients, the AHI was also measured when the drugs were administered separately. Measurements and Main Results: The participants' median (interquartile range) age was 53 (46-58) years and body mass index was 34.8 (30.0-40.2) kg/m². ato-oxy lowered AHI by 63% (34-86%), from 28.5 (10.9-51.6) events/h to 7.5 (2.4-18.6) events/h (P < 0.001). Of the 15/20 patients with OSA on placebo (AHI > 10 events/hr), AHI was lowered by 74% (62-88%) (P < 0.001) and all 15 patients exhibited a ≥50% reduction. Genioglossus responsiveness increased approximately threefold, from 2.2 (1.1-4.7)%/cm H₂O on placebo to 6.3 (3.0 to 18.3)%/cm H₂O on ato-oxy (P < 0.001). Neither atomoxetine nor oxybutynin reduced the AHI when administered separately. Conclusions: A combination of noradrenergic and antimuscarinic agents administered orally before bedtime on 1 night greatly reduced OSA severity. These findings open new possibilities for the pharmacologic treatment of OSA. Clinical trial registered with www.clinicaltrials.gov (NCT02908529).