The US Food and Drug Administration (FDA) has approved tirzepatide for chronic weight management in adults with obesity or overweight.
Eli Lilly & Company will market tirzepatide injections for weight management under the trade name Zepbound. It was approved in May 2022 for treating type 2 diabetes. The new indication is for adults with either obesity, defined as a body mass index (BMI) of 30 kg/m2 or greater, or overweight, with a BMI 27 kg/m2 or greater with at least one weight-related comorbidity, including hypertension, type 2 diabetes, or dyslipidemia.
“Obesity and overweight are serious conditions that can be associated with some of the leading causes of death, such as heart disease, stroke, and diabetes,” said John Sharretts, M.D., director of the Division of Diabetes, Lipid Disorders, and Obesity in the FDA’s Center for Drug Evaluation and Research. “In light of increasing rates of both obesity and overweight in the United States, today’s approval addresses an unmet medical need.”
A once-weekly injection, tirzepatide reduces appetite by activating two gut hormones, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). The dosage is increased over 4 to 20 weeks to achieve a weekly dose target of 5 mg, 10 mg, or 15 mg maximum.
Efficacy was established in two pivotal randomized, double-blind, placebo-controlled trials of adults with obesity or overweight plus another condition. One trial measured weight reduction after 72 weeks in a total of 2519 patients without diabetes who received either 5 mg, 10 mg or 15 mg of tirzepatide once weekly. Those who received the 15-mg dose achieved on average 18% of their initial body weight compared to placebo.
The other pivotal trial enrolled a total of 958 patients with type 2 diabetes. These patients achieved an average weight loss of 12% with once-weekly tirzepatide compared to placebo.
Another trial, which was presented at this year’s Obesity Week meeting and was published in Nature Medicine, showed clinically meaningful added weight loss for adults with obesity who did not have diabetes and who had already experienced weight loss of at least 5% after a 12-week intensive lifestyle intervention.
Another trial, which was reported at this year’s annual meeting of the European Association for the Study of Diabetes, found that tirzepatide continued to produce “highly significant weight loss” when the drug was continued in a 1-year follow-up trial. Those who discontinued taking the drug regained some weight but not all.
Tirzepatide can cause gastrointestinal side effects, such as nausea, diarrhea, vomiting, constipation, and abdominal pain or discomfort. Site reactions, hypersensitivity, hair loss, burping, and gastrointestinal reflux disease have also been reported.
The medication should not be used by patients with a personal or family history of medullary thyroid cancer or by patients with multiple endocrine neoplasia syndrome type 2. It should also not be used in combination with Mounjaro or another GLP-1 receptor agonist. The safety and effectiveness of the coadministration of tirzepatide with other medications for weight management have not been established.
Zepbound should go to market in the US by year’s end, with an anticipated monthly list price of $1060, according to a news release from Eli Lilly.
Miriam E. Tucker is a freelance journalist based in the Washington DC area. She is a regular contributor to Medscape, with other work appearing in the Washington Post, NPR’s Shots blog, and Diabetes Forecast magazine.
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