Sulthiame for Sleep Apnea: Clinical Trial Shows Drug Reduces Night-Time Breathing Pauses

What Is Sulthiame and How Does It Treat Sleep Apnea?

Sulthiame belongs to a class of drugs known as carbonic anhydrase inhibitors. It has been used for decades in parts of Europe to treat certain forms of childhood epilepsy, particularly benign rolandic epilepsy. Researchers hypothesized that its effects on blood carbon dioxide levels and respiratory chemoreceptor sensitivity could help stabilize breathing patterns during sleep.

Obstructive sleep apnea (OSA) is characterized by repeated episodes of partial or complete upper airway collapse during sleep, leading to breathing pauses known as apneas and hypopneas. These events cause oxygen desaturation, sleep fragmentation, and are associated with increased cardiovascular risk. By inhibiting carbonic anhydrase, sulthiame induces a mild metabolic acidosis that stimulates respiratory drive and may help keep the airway muscles more active during sleep, reducing the frequency and severity of breathing interruptions.

What Did the Clinical Trial Find?

The TESLA (Treatment of Sleep Apnea) trial, a randomized, double-blind, placebo-controlled study, evaluated sulthiame at different doses in patients with moderate to severe OSA. Results published in the New England Journal of Medicine showed that participants taking sulthiame experienced a meaningful reduction in their apnea-hypopnea index (AHI) — the standard measure of breathing pauses per hour of sleep — compared to those receiving placebo.

The drug was generally well tolerated, with the most common side effects including tingling sensations in the extremities (paresthesia), a known class effect of carbonic anhydrase inhibitors. Some patients also reported mild changes in taste perception. Researchers noted that the therapeutic effect appeared dose-dependent, with higher doses producing greater reductions in AHI. These findings are particularly significant because there is currently no widely approved pharmacological treatment for obstructive sleep apnea.

Why Is a Drug Alternative to CPAP So Important?

CPAP therapy remains the gold standard for treating moderate to severe obstructive sleep apnea, but adherence is a major clinical challenge. Studies consistently show that approximately half of patients prescribed CPAP do not use it consistently, citing discomfort, mask fit issues, claustrophobia, and lifestyle inconvenience. This leaves a substantial treatment gap for a condition that affects an estimated 936 million adults globally, according to Lancet Respiratory Medicine estimates.

Untreated sleep apnea is associated with a range of serious health consequences, including hypertension, atrial fibrillation, stroke, type 2 diabetes, and increased risk of motor vehicle accidents due to daytime sleepiness. A well-tolerated oral medication could transform management of this condition, particularly for patients with mild to moderate disease or those who have failed CPAP. While sulthiame is not yet approved for sleep apnea indication, further phase III trials are expected to clarify optimal dosing and long-term safety.