Atomoxetine-oxybutynin combo falls short of reducing AHI in OSA

The combination of atomoxetine and oxybutynin proves inadequate in lowering the apnoea–hypopnoea index (AHI) in Japanese patients with obstructive sleep apnoea (OSA), reveals a study. However, some patients experience a reduction in AHI.

A total of 17 patients with OSA were recruited to participate in this randomized, crossover, phase II, single-centre prospective trial, which sought to assess the effects of atomoxetine-oxybutynin therapy in Japanese OSA patients. The authors compared the effects of one night of atomoxetine 80 mg plus oxybutynin 5 mg with those of no medication administered before sleep.

AHI was the primary outcome, while secondary ones included nadir SpO₂, SpO₂ drop time, and sleep architecture. In addition, drug side effects and adverse events served as the safety endpoints.

No significant differences were seen in the values of AHI, nadir SpO₂, 3-percent oxygen desaturation index (ODI), 4-percent ODI, and SpO₂ drop time of <90 percent between patients treated with atomoxetine-oxybutynin therapy and those who did not receive medication.

Sleep architecture, on the one hand, showed a marked change. Specifically, the combination therapy increased sleep stage N1 (p<0.0001) and reduced stage N2 (p=0.03), rapid eye movement (p<0.0001), and sleep efficiency (p=0.02).

However, subanalysis revealed a reduction in AHI in five patients who showed response. Treatment responders appeared to have lower total sleep time and basal sleep efficiency than nonresponders (p=0.065).

In addition, none of the patients had severe adverse events or side effects.

“Future studies for identifying treatment response group characteristics are warranted,” the authors said.