The weight loss drug Mounjaro has been approved to treat sleep apnoea. How does it work? | UniSC | University of the Sunshine Coast, Queensland, Australia

Last week, Australia’s Therapeutic Goods Administration (TGA) approved the weight-loss drug Mounjaro to treat sleep apnoea, a condition in which breathing stops and starts repeatedly during sleep.

The TGA has indicated Mounjaro can be used to treat moderate to severe obstructive sleep apnoea in adults with obesity (a body-mass index of 30 or above).

The United States Food and Drug Administration approved the same drug for sleep apnoea last year.

So how could this drug, most commonly used for weight management and conditions such as type 2 diabetes, help people with sleep apnoea?

What is sleep apnoea?

Obstructive sleep apnoea is a common sleep disorder affecting almost 1 billion people worldwide. It’s characterised by repeated closures of the airway during sleep (called “apnoeas”). These can be partial or complete closures, meaning breathing can become shallow or stop completely.

As well as causing fragmented sleep, repeated collapse of the airway disrupts oxygen flow to the body. This strains the heart and contributes to an increased risk of cardiovascular and metabolic complications such as diabetes, high blood pressure and stroke.

One of the key risk factors for obstructive sleep apnoea is obesity. About 80% of people with the condition live with obesity. In fact, obesity and sleep apnoea share a bidirectional relationship, with obesity increasing the risk of developing sleep apnoea, and vice versa.

Obesity increases the risk of sleep apnoea by adding fat around the neck, which narrows the airway and impacts breathing during sleep.

In turn, sleep apnoea can contribute to weight gain by disrupting hormones that regulate hunger (ghrelin) and fullness signals (leptin). Fatigue also contributes, making it harder to maintain a healthy weight and easier to gain weight over time, creating a vicious cycle where each condition worsens the other.

Weight loss is a key part of treating sleep apnoea. It helps reduce the severity of symptoms and also lowers the risk of heart disease and other health problems which may arise as a result of sleep apnoea. However, achieving and sustaining weight loss through lifestyle changes is often challenging.

A continuous positive airway pressure (CPAP) machine is generally the first-line therapy for managing moderate to severe sleep apnoea. It delivers a steady stream of pressurised air through a mask to keep the airway open during sleep, which stabilises breathing and improves sleep quality.

Despite being an effective treatment, many people find the CPAP machine uncomfortable, unattractive or hard to use regularly. This can mean people don’t always stick to it.

Given the significant human and economic costs of sleep apnoea it’s pertinent to keep exploring new prevention and management strategies.

What is Mounjaro, and how could it help people with sleep apnoea?

Mounjaro is the brand name of a drug called tirzepatide. Elsewhere, it goes by other brand names, such as Zepbound.

Tirzepatide works by mimicking two hormone receptors in the gut, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP).

These two hormones play a key role in regulating our appetite, food intake and blood sugar levels. GLP-1 and GIP are released naturally in the body when we eat, but by mimicking their effects, tirzepatide allows people to feel fuller with smaller meals.

If a person is eating less overall, this can lead to weight loss.

In a study of 469 people with obesity and moderate to severe obstructive sleep apnoea, one year of tirzepatide treatment was associated with up to a 60% reduction in sleep apnoea severity. This is compared to a 3% reduction in people receiving a placebo.