Novo Nordisk (NYSE:NVO) shares fell and Eli Lilly and Co (NYSE:LLY) rose after a study found the US company's weight-loss drug may be more effective.
Lilly’s tirzepatide, branded as Mounjaro, was pitted against semaglutide, which Novo Nordisk (NYSE:NVO) makes under the Wegovy higher-dose brand for weight loss and Ozempic for type-2 diabetes, though the patients in the trial were all taking Ozempic.
Tirzepatide was found to lead to significantly greater weight loss than semaglutide in adults with overweight or obesity, the study, published in JAMA Network yesterday, revealed.
Tirzepatide is closely related to GLP-1 agonist drugs such as semaglutide, but is part of a class of drugs called GLP-1/GIP agonists, which work by mimicking two gut hormones: GLP-1 and glucose-dependent insulinotropic polypeptide (GIP).
The drugs were compared in a cohort of 18,386 patients, focusing on their effectiveness in achieving at least 5% weight loss within a year.
The study, spanning from May 2022 to September 2023, found that tirzepatide was more effective. On average, patients on tirzepatide saw weight reductions of 2.4%, 4.3%, and 6.9% at 3, 6, and 12 months, respectively, surpassing those on semaglutide.
"Although most adults with overweight or obesity experienced 5% or greater weight loss with treatment, the benefit was greater with tirzepatide," the researchers stated.
The incidence of gastrointestinal adverse events was similar between the two groups, underscoring tirzepatide's efficacy without additional risk.