Weight

Weight-loss drug approved to treat sleep apnea in Canada

Sleep apnea causes daytime sleepiness and is often tied to obesity

Health Canada has approved weight-loss drug Zepbound for treating obstructive sleep apnea in adults with obesity.

The department confirmed that the authorization granted on June 11 makes Zepbound the only GLP-1 drug in Canada approved for the sleep disorder that causes people to stop breathing temporarily because their upper airway is blocked.

That blockage can happen when throat muscles relax or when there is too much fatty tissue around the upper airway.

Sleep apnea causes daytime sleepiness and other potential risks, including high blood pressure, heart attacks and strokes, said Dr. Mandeep Singh, a clinician investigator in sleep science at University Health Network in Toronto.

It is often associated with obesity and can be improved with weight loss, he said.

The active ingredient in Zepbound is tirzepatide, which acts on both GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide) hormone receptors to reduce appetite, leading to weight loss.

Eli Lilly's tirzepatide medications, including Zepbound and diabetes drug Mounjaro, are competitors to Novo Nordisk's semaglutide drugs Ozempic and Wegovy.

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Health Canada spokesperson Marie-Pier Burelle said tirzepatide should be injected once a week and used alongside a reduced calorie diet and increased physical activity in adults with obesity, measured by a body mass index (BMI) of 30kg/m2 or higher.

The drug is "not an immediate replacement" for continuous positive airway pressure — or CPAP — that is a first-line therapy for moderate to severe sleep apnea, Burelle said.

"Patients taking Zepbound should not stop using their CPAP machine without a doctor's guidance," she said.

Aims to prevent breathing interruptions

Health Canada's approval follows Phase 3 clinical trials with patients who had both obesity and sleep apnea.

The studies found sleep apnea patients on tirzepatide who weren't using a CPAP machine had 25 fewer breathing interruptions per hour compared with five fewer breathing disruptions among those taking a placebo.

Among patients using a CPAP machine, researchers found 29 fewer breathing interruptions an hour among patients taking tirzepatide, compared with six who were taking a placebo.

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Singh, who was not involved in the clinical trials, said the severity of obstructive sleep apnea is defined by the number of breathing interruptions per hour of sleep.

People with mild sleep apnea generally have about five to 14 interruptions per hour, he said, while those with moderate sleep apnea have 15 to 30 interruptions, and patients with severe sleep apnea have more than 30 an hour.

"A reduction of 25-29 events per hour would represent a meaningful change, potentially shifting someone from severe into a lower-severity category depending on where they started," Singh said. "I think that's a welcome step towards offering, you know, another option for patients who have obstructive sleep apnea."

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There are signs that losing weight on other GLP-1 drugs could also benefit people with sleep apnea, but that's based on anecdotal observation by clinicians and there isn't research evidence yet to make that claim, Singh said.

He said more study is needed to see if tirzepatide could have an effect on sleep apnea among patients who don't have obesity.

"If we can kind of, like, tease out what is the effect of weight loss versus what is the direct effect of these medications on the upper airway, that will be very interesting."

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The most common side effects of GLP-1 drugs, including tirzepatide, are nausea, vomiting, diarrhea and constipation. More serious but much less likely side effects include inflammation of the pancreas, bowel obstruction and gallstones.

"Whenever a patient is diagnosed to have obstructive sleep apnea, we have a discussion about risks and benefits of the various treatment options available to them. And this medication will go on that list of options when we discuss the risks and benefits," Singh said.

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