A once-nightly pill significantly reduced the severity of obstructive sleep apnea in a large phase 3 clinical trial, offering a potential option for patients who cannot tolerate the CPAP machines that remain the standard treatment. Results from the trial, called SynAIRgy, were presented at a 2026 American Thoracic Society conference and published in the American Journal of Respiratory and Critical Care Medicine.
The drug, known as AD109, combines two existing compounds, aroxybutynin and atomoxetine, designed to target the neuromuscular mechanisms that let the upper airway collapse during sleep, rather than mechanically holding it open the way CPAP does. Over six months, 646 adults with mild-to-severe obstructive sleep apnea at 69 sites in the United States and Canada took either the drug or a placebo nightly. Patients on AD109 saw their apnea-hypopnea index, the standard measure of breathing interruptions per hour of sleep, fall by about 44 percent, compared with an 18 percent drop in the placebo group, according to a summary of the findings. More than 40 percent of treated patients moved into a less severe disease category, and 18 percent reached what researchers classified as complete disease control. Oxygen desaturation and "hypoxic burden," a measure of how long blood oxygen runs low overnight, also improved.
Obstructive sleep apnea is common and, left untreated, is linked to higher long-term risk of hypertension, heart disease and stroke. CPAP machines remain the most effective treatment available, but many patients find them difficult to use consistently — the trial enrolled only participants who had already rejected or could not tolerate CPAP, the specific gap researchers say AD109 is designed to address.
"An oral pill that targets the underlying neuromuscular drivers of airway collapse during sleep could help address this gap and broaden the range of effective options."
Patrick J. Strollo, University of Pittsburgh
Strollo, a professor of medicine at the University of Pittsburgh and one of the trial's investigators, said the results point to a genuine unmet need in sleep medicine. The trial was funded by Apnimed, the drug's developer, which has submitted a New Drug Application to the FDA; the agency has granted AD109 Fast Track designation, with a target decision date in the first quarter of 2027, meaning the drug is not yet available to patients. Side effects, including dry mouth, nausea, insomnia and difficulty urinating, led about 21 percent of participants to stop taking the drug during the trial — a discontinuation rate that regulators and independent specialists will likely weigh heavily during review. Because Apnimed funded and helped run the study, independent replication and FDA scrutiny remain important tests before any approval.
If approved, AD109 would become one of the first pharmaceutical treatments aimed directly at the airway-collapse mechanism behind OSA, rather than at daytime sleepiness or mechanical support. A companion mechanistic study, published alongside the trial, outlines how the drug's dual action on bladder and norepinephrine pathways is thought to translate into steadier airway muscle tone overnight. Longer-term follow-up data, if the drug reaches the market, will be needed to show whether the six-month improvements persist over years of nightly use.
