New Weight-Loss Drug Cuts Knee Pain and Sleep Apnoea in Trial

A large-scale trial has found that retatrutide — a new type of injectable drug that targets three hormone receptors at once — helped people with obesity lose significant amounts of weight while also easing two conditions closely linked to excess weight: osteoarthritis (joint inflammation causing pain and stiffness) in the knee, and obstructive sleep apnoea (repeated pauses in breathing during sleep).

The results come from the TRIUMPH-1 trial, a phase 3 study — the final stage of testing before a drug can be considered for regulatory approval. Participants had obesity, and the trial measured not just weight change but also pain levels in the knee and the frequency of breathing interruptions during sleep. All three outcomes improved with the drug.

Retatrutide works differently from existing weight-loss drugs such as semaglutide. Rather than acting on one or two hormone pathways, it targets three: GLP-1, GIP, and glucagon receptors. That combination is designed to suppress appetite and increase the body’s energy use more aggressively than single or dual-receptor drugs.

The findings matter because knee osteoarthritis and obstructive sleep apnoea are both conditions that worsen with excess body weight and are difficult to treat in people who remain obese. A drug that addresses weight and these complications together could change how doctors approach treatment — though retatrutide is not yet approved for use in the UK, and no timeline for NHS availability has been announced.

Meanwhile, the New England Journal of Medicine published the full trial results. Retatrutide’s manufacturer has not yet submitted a licence application to the Medicines and Healthcare products Regulatory Agency (MHRA), which oversees drug approvals in Great Britain.

Anyone concerned about obesity, knee pain, or sleep apnoea should speak to their GP in the first instance, or call NHS 111 for advice.