Shares in Novo Nordisk (NYSE:NVO), Denmark-based maker of obesity drug Wegovy, fell 1.8% in premarket trading Tuesday after newly released data showed that Eli Lilly's (NYSE:LLY) competing treatment, Mounjaro, leads to faster and greater weight loss.
The analysis, published on Monday in the medical journal JAMA Internal Medicine, reviewed health records and other data to compare the weight loss results of overweight and obese individuals taking tirzepatide, the active ingredient in Lilly's Mounjaro and Zepbound, with those taking semaglutide, the main ingredient in Novo Nordisk's Wegovy and Ozempic.
In the absence of head-to-head randomized controlled trials directly comparing the two drugs, researchers analyzed weight loss trajectories using health records and pharmacy dispensing data from 9,193 patients on Mounjaro and an equal number of closely matched patients on Ozempic. The average participant weighed 242 pounds (110 kg), with about half having type 2 diabetes.
After adjusting for individual risk factors, the study found that patients on 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 those on Ozempic.
"This analysis compared the weight loss outcomes of semaglutide (Ozempic) and tirzepatide (Mounjaro) and did not include Wegovy even though weight loss was the main objective assessed,” Novo Nordisk said in a statement.
The company stressed that the best way to compare the two drugs is through a head-to-head clinical trial, noting that no such trial has been completed yet.
Historically the world's largest producers of insulin, Novo Nordisk and Eli Lilly are the first to market with highly effective weight-loss drugs. The market for these treatments is booming, with analysts predicting it could reach $150 billion in annual sales by the early 2030s.