Around one billion people worldwide have obstructive sleep apnea. A significant proportion of them stop breathing, repeatedly, every single night — sometimes hundreds of times — while their partners lie awake listening, and their own bodies slowly accumulate the damage of chronic oxygen deprivation: elevated cardiovascular risk, cognitive decline, metabolic disruption, exhaustion that no amount of sleep seems to fix.
For decades, the only widely available treatment has been the CPAP machine: a mask strapped over the face that delivers continuous pressurised air to hold the airway open. For many people, it works well. For many others — up to 50% of CPAP users report abandoning it within a year — the mask is intolerable. Too uncomfortable. Too intrusive. Too isolating. A daily reminder of a condition that already disrupts sleep, now disrupting sleep in a different way.
Until now, there has been no approved drug treatment for obstructive sleep apnea.
That is about to change.
**The FLOW Trial**
A Phase 2 clinical trial called FLOW, conducted across four European countries and involving 298 patients with moderate to severe obstructive sleep apnea, has produced results that researchers are describing as a landmark. The trial tested sulthiame — a drug previously approved in some European countries for a rare form of childhood epilepsy — at different doses against a placebo.
The headline finding: patients on the higher dose of sulthiame experienced **up to 47% fewer breathing interruptions** compared to those on placebo. They showed improved blood oxygen levels. Their sleep quality measurably improved.
The results were published in *The Lancet* and have since been widely reported across the medical and science press.
**How It Works**
Sulthiame is a carbonic anhydrase inhibitor — a class of drugs that affects the body's regulation of carbon dioxide and breathing drive. In sleep apnea, the problem is that the upper airway collapses during sleep, blocking the passage of air. Sulthiame addresses this by stabilising the brain's respiratory control system and increasing the signal to breathe, reducing the threshold at which the airway collapses.
In simple terms: it teaches the body to breathe more consistently during sleep, even when the upper airway is under pressure.
'The prospect of having a drug-based treatment option is exciting,' said researchers from the University of Gothenburg, which was involved in the trial. 'These results justify larger, longer studies to confirm sustained effects and safety in broader patient groups.'
**Why This Matters**
The numbers behind sleep apnea are staggering. Estimates suggest **1 billion people** have some form of the condition globally. Many are undiagnosed — sleep apnea often presents as nothing more exotic than snoring, and many sufferers and their families have no idea that the snoring is accompanied by repeated cessation of breathing.
Of those who are diagnosed and prescribed CPAP, a large fraction cannot sustain use. Compliance rates are poor. And for those who cannot or will not use CPAP, there has been nothing: no pharmaceutical alternative, no simple intervention, no pill.
Sulthiame would change that equation entirely. A daily tablet, already proven safe enough to be approved for children with epilepsy in some countries, showing meaningful efficacy in a randomised controlled trial published in one of the world's most prestigious medical journals.
**What Comes Next**
The FLOW trial is Phase 2 — a crucial milestone, but not yet the end of the road. Phase 3 trials, involving larger populations over longer timescales, will be needed before sulthiame can seek regulatory approval specifically for sleep apnea.
That process will take years. But the trajectory is clear. The drug works on a biological mechanism. The trial results hold up to scrutiny. The unmet need is enormous.
For the millions of people who lie awake in silence while their airways collapse — and for the millions more who don't yet know that's what's happening to them — sulthiame is a reason, cautious but genuine, for optimism.
The first pill for sleep apnea may finally be on its way. 😴
*Sources: The Lancet (October 2025, updated March 2026) · University of Gothenburg (gu.se) · ScienceDaily (March 11, 2026) · Gizmodo · Apnimed · EudraCT NCT05236842*
