An experimental once-daily pill reduced sleep apnea-related breathing interruptions by about 44% in a phase 3 trial.
The study included 646 adults who could not tolerate or declined standard PAP therapy.
The medication improved several measures of nighttime breathing and oxygen levels, but side effects led some participants to stop treatment.
For people with obstructive sleep apnea (OSA), keeping the airway open during sleep can be a challenge. The condition causes repeated blockages in the upper airway, which can interrupt breathing and reduce oxygen levels during the night.
Continuous positive airway pressure, or CPAP, is a common treatment, but not everyone is able or willing to use it long term. That has researchers looking for other approaches.
One experimental option is AD109, a once-daily pill that combines two medications: aroxybutynin and atomoxetine. The drugs are designed to increase the activity of muscles in the upper airway during sleep, making the airway less likely to collapse.
"In many other chronic diseases, such as cardiovascular disease, asthma, or type 2 diabetes, it would be unthinkable for the majority of diagnosed patients to remain untreated or undertreated,” first author Patrick John Strollo, MD, a sleep medicine physician at the University of Pittsburgh Medical Center, said in a news release. “Yet that remains the reality in OSA.
"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 for patients who remain untreated today."
How researchers tested the pill
The phase 3 SynAIRgy trial included 646 adults with mild to severe obstructive sleep apnea who had either been unable to use or had refused positive airway pressure therapy.
Researchers randomly assigned participants to receive either AD109 or a placebo, meaning a pill without the active medications. Neither the participants nor researchers knew who received which treatment during the trial.
The study lasted 26 weeks, or about six months, and was conducted at 69 sites in the U.S. and Canada. Participants underwent overnight sleep studies at the beginning of the trial and again during the study.
Researchers measured their apnea-hypopnea index, or AHI, which tracks how often breathing is interrupted during sleep, along with oxygen levels and other measures of sleep and fatigue.
What the study found
After 26 weeks, people taking AD109 had an estimated 44.1% reduction in their AHI, compared with a 17.6% reduction among those taking the placebo. The medication also improved measures of nighttime oxygen problems, including the number of times oxygen levels dropped and the amount of time participants experienced low oxygen.
More than 40% of people taking AD109 moved into a less severe sleep apnea category, according to the study. However, the medication did not produce a statistically significant improvement in the study's measure of fatigue.
The treatment also had side effects. The most commonly reported were dry mouth, nausea, insomnia, and difficulty urinating. About 21% of participants taking AD109 discontinued treatment because of adverse events, compared with about 3% of those taking the placebo.
For consumers, the findings suggest that an oral medication could eventually provide another treatment option for some people with sleep apnea who cannot use PAP therapy. But AD109 is still an investigational treatment, so the study does not mean that people with sleep apnea should replace their current treatment with the medication.