LONDON: Tirzepatide, the active ingredient in Eli Lilly’s medications Mounjaro and Zepbound, has been found to achieve greater weight loss outcomes compared to semaglutide, the active component in Novo Nordisk’s drugs Ozempic and Wegovy, a new research study found.
Published Monday in JAMA Internal Medicine, the study marks the first direct comparison between these two medications designed for weight loss. Since receiving approval for weight management in late 2023, Zepbound has emerged as a formidable competitor to Wegovy, demonstrating notable advantages in clinical efficacy.
The research, led by Tricia Rodriguez, a principal applied scientist at Truveta Research, analyzed electronic health records from over 41,000 adults suffering from overweight or obesity, including those with Type 2 diabetes. Of these participants, more than 9,100 were prescribed tirzepatide, while over 32,000 were prescribed semaglutide.
Key findings from the study revealed that patients on tirzepatide achieved remarkable weight loss milestones. Those on the highest dose of tirzepatide saw a reduction of approximately 21% in body weight over 72 weeks, compared to around 15% for patients on Wegovy after 68 weeks.
“We’ve observed substantial increases in the use of GLP-1s over the past year, yet there’s been a lack of head-to-head data comparing these medications,” noted Rodriguez.
Participants on semaglutide experienced an average weight loss of 3.6% after 3 months, 5.8% after 6 months, and 8.3% after 12 months. In contrast, those on tirzepatide reported higher average weight reductions: 5.9% after 3 months, 10.1% after 6 months, and 15.3% after 12 months.
Rodriguez emphasized that while both medications demonstrated clinically meaningful weight loss, tirzepatide consistently delivered superior results.
The study also found no significant difference in the incidence of serious side effects, such as gastroparesis, between tirzepatide and semaglutide.
Both medications belong to the GLP-1 class and function similarly by mimicking hormones that regulate appetite and food intake. However, tirzepatide also mimics a second hormone, GIP, which enhances sugar and fat metabolism in addition to suppressing appetite.
However, researchers caution that further randomized controlled trials are necessary to definitively determine which medication offers the best overall benefits. Lilly has already initiated a phase 3 trial involving 700 patients to directly compare tirzepatide and semaglutide, with completion expected in November.
