While drugs such as Wegovy target a single gut hormone, retatrutide is part of a new class of GLP-1 drugs that target three hormone receptors.
By Adam Kovac edited by Claire Cameron
Getty Images/Sweet Bun Factory
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The next generation of glucagonlike peptide 1 (GLP-1) weight-loss drugs has taken another step toward approval by the U.S. Food and Drug Administration. In results from a new clinical trial from pharmaceutical company Eli Lilly, a weekly injection of 12 milligrams (0.19 grains) of retatrutide for 80 weeks helped people lose nearly 30 percent of their body weight, or about 70 pounds on average, according to a company statement.
That puts retatrutide essentially on par with bariatric surgery, says Daniel Drucker, a professor of medicine at the University of Toronto, who previously consulted with Eli Lilly but was not involved in the trial. “This has always been the GLP-1 drug that we considered to be the most potent, [with] the greatest weight loss,” he says.
Contrary to other approved GLP-1 drugsWegovy and Zepbound, which also targets the gut hormone GLP-1, retatrutide targets three receptors known to regulate appetite: GLP-1, glucagon and glucose-dependent insulinotropic polypeptide (GIP). Targeting more than one receptor appears to enhance the weight loss effects of drugs. For example, tirzepatide (sold under the brand name Zepbound) targets two receptors, and clinical trials suggest it helps people lose more weight than semaglutide (the active ingredient in Wegovy), which targets only one.
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The new retatrutide study is a Phase 3 clinical trial – the gold standard needed to gain eventual FDA approval – called TRIUMPH-1. Participants were all classified as overweight or obese, with an average baseline weight of 248.5 pounds. At the highest doses of retatrutide tested – 12 milligrams (0.19 grains) – participants lost an average of 28.3 percent of their weight.
“TRIUMPH-1 highlights the importance of options and the potential of retatrutide to help people at different stages of their obesity journey,” Kenneth Custer, executive vice president of Eli Lilly and president of Lilly Cardiometabolic Health, said in a study. statement.
The results also highlighted potential side effects: About a third of participants reported nausea or diarrhea, while about a quarter reported constipation. Between 10 percent and a quarter experienced vomiting, depending on the dose. These effects were as expected, Drucker says.
“If approved…, this would be the drug that people who need to lose the most weight would turn to,” he adds.
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