Epilepsy drug shows promise for obstructive sleep apnoea

Sulthiame, a drug currently in use for epilepsy, has been shown to reduce symptoms of obstructive sleep apnoea (OSA), according to the results of a clinical trial presented at last month’s European Respiratory Society (ERS) Congress by Professor Jan Hedner.

Patients with OSA often snore loudly, with their breathing starting and stopping during the night, which may cause them to wake up several times. Not only does this cause tiredness, it can also increase the risk of high blood pressure, stroke, heart disease and type 2 diabetes. OSA is very common, but many people do not realise they have the condition.

“The standard treatment for obstructive sleep apnoea is sleeping with a machine that blows air through a face mask to keep the airways open,” said Hedner, from Sahlgrenska University Hospital and the University of Gothenburg. “Unfortunately, many people find these machines hard to use over the long term, so there is a need to find alternative treatments. We also a need better understanding of the underlying mechanisms in OSA to help clinicians give more personalised treatment.”

The new trial was a double-blind, randomised, placebo-controlled trial — the gold standard in medical research. It involved 298 people with OSA being treated at 28 different centres in Spain, France, Belgium, Germany and the Czech Republic. All the patients could not tolerate or refused to use continuous positive airway pressure (CPAP) machines or mouthpieces designed to keep the airways open.

The patients were assessed with polysomnography three times during the trial: at the beginning, after four weeks and after 12 weeks. Polysomnography measures breathing, levels of oxygen in the blood, heart rhythm, eye movements, and brain and muscle activity during a night of sleep.

The patients were divided into four groups: 74 people took 100 mg of sulthiame daily, 74 took 200 mg, 75 took 300 mg and the remaining 75 took a placebo. Sulthiame is a drug that targets the respiratory system by inhibiting an enzyme called carbonic anhydrase and stimulating the upper airway muscles.

The people taking sulthiame had fewer pauses in their breathing and higher levels of oxygen in their blood during sleep. A measure of the frequency of respiratory pauses during sleep, called AHI3a, was 17.8% lower for patients taking the lowest dose, 34.8% lower for patients on the medium dose and 39.9% lower for patients on the highest dose. When researchers used another measure called AHI4, the effect of the treatment was close to a 50% reduction of respiratory pauses with more profound lowering of oxygen levels. OSA patients who had been feeling sleepy during the daytime also felt less so when they took sulthiame.

“People taking sulthiame in the trial had a reduction in OSA symptoms such as stopping breathing during the night and feeling sleepy during the day,” Hedner said. “Their average levels of oxygen in the blood were also improved with the treatment. This suggests that sulthiame could be an effective treatment for OSA, especially for those who find they cannot use the existing mechanical treatments.

“Although sulthiame is already available as a treatment for childhood epilepsy, we still need to carry out a phase III study to confirm the beneficial respiratory effects of this drug in a larger group of patients with OSA.”

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