Trial Shows Pill Reduces Sleep Apnea Events by Up to 35%

A phase 2 clinical trial has demonstrated that a medication can significantly reduce breathing interruptions in patients with obstructive sleep apnea, offering potential relief for the millions who struggle with the standard treatment.

According to results published in The Lancet, the FLOW trial tested sulthiame — a drug already approved for epilepsy in Europe — across 298 patients with moderate to severe sleep apnea at 28 sites in five European countries. Patients receiving the highest dose (300mg daily) experienced a 34.6% reduction in apnea-hypopnea events compared to placebo, meeting the trial's primary endpoint.

The randomized, double-blind, placebo-controlled study found a clear dose-response effect: the 100mg dose produced a 16.4% reduction, 200mg produced 30.2%, and 300mg produced 34.6%. All doses showed statistically significant improvement over placebo.

"We have been working on this treatment strategy for a long time, and the results show that sleep apnea can indeed be influenced pharmacologically," said Jan Hedner, senior professor of pulmonary medicine at the Sahlgrenska Academy, University of Gothenburg, and lead author of the study. "It feels like a breakthrough."

Obstructive sleep apnea occurs when the upper airway collapses repeatedly during sleep, causing breathing to stop and oxygen levels to drop. The standard treatment is a CPAP machine, which uses pressurized air to keep airways open. But many patients abandon the device — up to half stop using it within a year due to discomfort.

Sulthiame is a carbonic anhydrase inhibitor that appears to work by stabilizing respiratory control and increasing respiratory drive, making airway collapse less likely. The drug was generally well-tolerated in the trial, with most side effects mild and temporary.

The findings represent a potential paradigm shift for sleep apnea treatment. While tirzepatide (marketed as Mounjaro or Zepbound) received FDA approval for sleep apnea in late 2024, it works primarily through weight loss. Sulthiame targets a different mechanism and could benefit patients regardless of weight.

The study authors noted that larger and longer trials are needed to determine whether the effects sustain over time and whether the treatment is safe for broader patient groups.

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This article synthesizes peer-reviewed Lancet publication data with reporting from ScienceDaily and University of Gothenburg. The story was produced through the full editorial pipeline: wire triage, beat reporting, fact-check (which corrected the efficacy figure from 47% to 34.6%), and editor review.