Obstructive sleep apnea, commonly known as OSA, affects millions of people worldwide and is linked to serious health risks including cardiovascular disease, fatigue, cognitive decline, and poor sleep quality. While continuous positive airway pressure therapy, often called CPAP or PAP therapy, remains the standard treatment, many patients struggle to tolerate the equipment long term. A newly published Phase 3 clinical trial suggests that an investigational oral medication called AD109 may offer a new treatment option for adults unable or unwilling to use PAP therapy.
The study, published in the American Journal of Respiratory and Critical Care Medicine, evaluated the safety and effectiveness of AD109 over a 26 week period in adults with mild to severe obstructive sleep apnea. Researchers found that the once nightly pill significantly reduced airway obstruction and improved oxygen levels during sleep compared with placebo treatment.
AD109 is an investigational oral drug developed to address one of the underlying causes of obstructive sleep apnea, which is reduced muscle tone in the upper airway during sleep. The medication combines two compounds:
Together, these medications are designed to stimulate the muscles that help keep the airway open during sleep. Unlike PAP therapy, which mechanically keeps the airway open using pressurized air, AD109 aims to improve neuromuscular control naturally during sleep.
Researchers believe this mechanism may make the drug useful for a broad range of sleep apnea patients, including those who are not obese and those who have struggled with traditional therapies.
The clinical trial, known as SynAIRgy, enrolled 646 adults with mild to severe obstructive sleep apnea across 69 centers in the United States and Canada. Participants either could not tolerate PAP therapy or had refused to use it altogether.
The study was randomized, double blind, and placebo controlled, which is considered the gold standard for medical research.
The patient population reflected a broad spectrum of sleep apnea severity:
This diversity is notable because many previous sleep apnea studies focused heavily on overweight male populations.
The primary measurement used in the study was the apnea hypopnea index, or AHI, which tracks breathing interruptions during sleep.
At 26 weeks:
Researchers also noted that improvements were visible as early as four weeks after treatment began.
Patients taking AD109 shifted from the moderate sleep apnea category toward the mild category on average, suggesting clinically meaningful improvement.
Beyond reducing breathing interruptions, AD109 improved oxygen related outcomes during sleep.
The medication significantly improved:
Hypoxic burden refers to the total amount of oxygen deprivation experienced during sleep. This measure is increasingly recognized as important because repeated nighttime oxygen drops are associated with heart disease, metabolic dysfunction, and increased mortality risk.
Researchers observed a nearly 45% reduction in hypoxic burden among AD109 users compared with minimal change in the placebo group.
One of the more encouraging findings involved treatment response rates.
By week 26:
The medication also reduced snoring and improved breathing during both REM and non REM sleep.
Although the results were promising, the study also revealed important tolerability concerns.
The most common side effects included:
About 21.2% of participants taking AD109 stopped treatment because of side effects, compared with only 3.1% in the placebo group.
Most side effects were considered mild, and serious treatment related adverse events were not reported. Researchers noted that many discontinuations occurred early in treatment, suggesting that patients who tolerate the medication initially may continue successfully long term.
There were also small increases in heart rate among some participants receiving AD109, though blood pressure changes were generally minimal.
Obstructive sleep apnea remains significantly undertreated worldwide. Experts estimate that up to 80% of individuals with OSA remain undiagnosed, while many diagnosed patients discontinue PAP therapy within the first year.
Current alternatives such as oral appliances, surgery, or weight loss interventions are not suitable or effective for every patient. Because AD109 is taken orally once nightly, researchers believe it could appeal to patients seeking a simpler and less invasive treatment option.
Importantly, the medication appeared effective across multiple subgroups, including:
This broad applicability may distinguish AD109 from other therapies that only work well in select populations.
Despite encouraging findings, several limitations should be considered.
First, the relatively high discontinuation rate may have reduced the apparent effectiveness of the medication in the full analysis. Researchers suggested that allowing lower dosing options in future studies could improve tolerability.
Second, most participants had mild to moderate sleep apnea, which may limit how well the results apply to individuals with extremely severe disease.
Finally, because the trial was conducted only in the United States and Canada, results may not fully represent global patient populations.
The SynAIRgy trial represents one of the largest pharmacologic studies ever conducted for obstructive sleep apnea. If approved by regulators, AD109 could become one of the first oral medications specifically designed to treat the neuromuscular dysfunction underlying OSA.
While PAP therapy will likely remain the standard first line treatment, AD109 may eventually provide an alternative for patients who cannot tolerate existing devices.
Additional long term studies and regulatory review will determine whether the drug ultimately reaches the market, but the current data suggest meaningful progress in the search for easier and more accessible sleep apnea therapies.
Strollo PJ Jr, Farkas R, Taranto-Montemurro L, Cronin J, Patel SR, et al. “Aroxybutynin and atomoxetine (AD109) for obstructive sleep apnea: a randomized phase 3 trial (SynAIRgy).” American Journal of Respiratory and Critical Care Medicine. 2026. DOI: 10.1093/ajrccm/aamag215.
This article is for informational and educational purposes only and does not constitute medical advice, diagnosis, or treatment. AD109 remains an investigational medication and has not been universally approved for clinical use. Patients should consult a qualified healthcare professional before making any decisions regarding sleep apnea treatment or medication use.
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