Over a billion people worldwide have obstructive sleep apnea — a condition where the airway repeatedly collapses during sleep, causing breathing to stop tens or hundreds of times each night. The health consequences are serious: increased risk of heart disease, stroke, diabetes, and premature death. Yet for decades, the only reliable treatment has been a CPAP machine, a device that straps to your face and pumps pressurised air all night. Many people find it intolerable and stop using it within months.
Now a randomised controlled trial published in The Lancet has produced one of the most promising results ever seen for a pharmacological approach to sleep apnea — and the drug behind it isn't even new.
Sulthiame: An Old Drug With a New Purpose
Sulthiame has been used in Europe as an epilepsy medication for decades. Researchers at Apnimed noticed that its mechanism — stabilising the brain's breathing control signals — might also prevent the airway collapse that causes sleep apnea. The hypothesis turned out to be correct.
The FLOW trial enrolled 298 adults with moderate to severe sleep apnea across multiple European centres. Participants received either a placebo or one of three doses of sulthiame (100mg, 200mg, or 300mg) once daily for 15 weeks. The primary measure was the apnea-hypopnea index (AHI) — essentially, how many times per hour breathing stopped or significantly slowed.
At the highest dose, patients experienced 47% fewer breathing interruptions compared to placebo. Nocturnal oxygen levels improved measurably. Side effects were generally mild and temporary.
'This Could Change Everything for Patients'
Sleep specialists have long described an unmet need for a tablet treatment. CPAP is effective but only for those who actually use it — and adherence rates are poor globally. A once-daily pill that achieves comparable results would represent a transformation in how the condition is managed.
"The results are exciting because sulthiame appears to address one of the fundamental biological mechanisms causing sleep apnea," said one of the trial investigators. "This isn't just masking symptoms — it's targeting the neural control of breathing."
The trial is a Phase 2 study, meaning larger Phase 3 trials are still needed before regulatory approval. But Phase 2 results of this magnitude in a disease with so little pharmacological progress are highly significant.
More Than One Billion People Could Benefit
The World Health Organization estimates that 936 million adults have moderate to severe sleep apnea globally, with the true total including milder cases likely exceeding a billion. The condition is substantially underdiagnosed — many people don't know they have it until a partner notices they stop breathing at night, or until they develop cardiovascular complications.
For those who are diagnosed, sulthiame — if approved — would represent the first tablet option ever validated by a major randomised trial. Apnimed has announced plans to proceed with Phase 3 studies.
Sources: The Lancet · Apnimed · Gizmodo · ScienceAlert · The Week, March 2026
