Lilly's Mounjaro leads to more and faster weight loss than Novo obesity drug, data analysis finds

[November 28, 2023]  By Nancy Lapid

(Reuters) - Overweight or obese adults lost more weight and shed pounds faster using Eli Lilly's Mounjaro than those taking Novo Nordisk's popular rival weight loss drug, according to an analysis of health records and other data.

Within one year of starting treatment, 42.3% of those taking tirzepatide - the active ingredient in Mounjaro and Zepbound - had lost at least 15% of their weight, compared with 19.3% among patients taking semaglutide - the main ingredient in Wegovy and Ozempic, the study published on medRxiv in advance of peer review found.

After accounting for individual risk factors, patients taking Mounjaro were 76% more likely to lose at least 5% of their body weight, more than twice as likely to lose at least 10%, and more than three times as likely to lose at least 15%, compared to patients taking Ozempic, the report said.

In the absence of head-to-head randomized controlled trials comparing the two drugs, researchers used electronic health records and pharmacy dispensing data to analyze weight loss trajectories in 9,193 patients receiving Mounjaro and the same number of closely matched patients receiving Ozempic. The average participant weighed 242 pounds (110 kg), and about half had type 2 diabetes.

After 3 months of treatment, patients on Mounjaro had lost an average of 2.3% more body weight than those taking Ozempic, the study also found. By 6 months, the difference had widened to 4.3%, and by 12 months, the Mounjaro group had lost an average of 7.2% more weight.

Rates of gastrointestinal adverse events were similar between groups, the researchers said.

Boxes of Ozempic and Mounjaro, semaglutide and tirzepatide injection drugs used for treating type 2 diabetes and made by Novo Nordisk and Lilly, is seen at a Rock Canyon Pharmacy in Provo, Utah, U.S. March 29, 2023. REUTERS/George Fre/File Photo

The researchers note that Ozempic and Mounjaro are both intended for use by people with type 2 diabetes, but half of the study participants were using the drugs for weight loss only, which may have impacted the results.

Novo Nordisk in an emailed statement said, "The doses of semaglutide evaluated in this analysis have not been investigated for chronic weight management, and there are no head-to-head trials that have (been) reported which evaluate Wegovy and tirzepatide."

An Eli Lilly spokesperson said the company does not promote or encourage the off-label use of any of its medicines, although its drug is now approved for weight loss.

A trial is underway comparing the weight loss formulations of the two injected medicines in patients overweight or obese but without type 2 diabetes. Those results are not expected until 2025.

Meanwhile, the Novo spokesperson pointed out that the study report notes: "This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice.”

(Reporting by Nancy Lapid; editing by Bill Berkrot)

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