Retatrutide Shows 25% Weight Loss in Obesity Trial

New obesity drug candidate demonstrates significant weight reduction in Phase 3 trial with potential to lower global health costs.

Retatrutide, an experimental weekly injection developed by Eli Lilly, achieved an average weight loss of 25% of starting body weight at the highest 12 mg dose after 80 weeks in a Phase 3 trial involving 2,339 adults with obesity without diabetes. By 104 weeks (80 weeks plus a 24-week extension), participants continued on the 12 mg dose lost 29.9% of their body weight. The drug also showed measurable benefits for knee osteoarthritis and obstructive sleep apnea, reducing pain scores by 4.1 points and breathing interruptions by 32.1 per hour compared to placebo. However, 42% of participants experienced nausea and 11% discontinued treatment due to adverse events.

The drug works by targeting multiple receptors—GLP-1, GIP, and glucagon—to simultaneously reduce food intake and increase energy expenditure. This multi-action approach differs from existing obesity therapies, though the trial did not compare it to semaglutide or tirzepatide.

If approved and made affordable, retatrutide could reduce obesity-related health costs globally by addressing conditions like diabetes, joint pain, and sleep apnea that strain healthcare systems. Current obesity treatments often require complex regimens or carry higher risks, so a single weekly injection with this level of efficacy could improve access to weight management for millions.

What remains to be confirmed: cardiovascular safety data, long-term effects beyond two years, and whether the drug’s benefits persist without prohibited weight-loss therapies. The trial’s two-year results only reflect participants who continued treatment—meaning outcomes may differ for those who stopped early. This drug shows promise but requires rigorous testing before it can move toward widespread availability.

Source: ScienceAlert