Patients taking the obesity drug Zepbound lost 47% more weight than those who were given Novo Nordisk's Wegovy in the first large, head-to-head trial of the medications.

In a 751-person trial sponsored by Eli Lilly, Zepbound helped patients lose an average of 20.2% of their weight after 72 weeks compared to 13.7% for the group treated with Wegovy.

Participants were either obese or overweight and had an additional related health issue such as obstructive sleep apnea or heart disease. None of the patients had diabetes.

U.S. approvals for the drugs were based on separate trials in which Zepbound helped patients lose more than 22% of their weight after 72 weeks, while Wegovy led to a 15% weight loss after 68 weeks.

Lilly said it would publish the results in a peer-reviewed journal and present it at a medical meeting next year.

Novo Nordisk said it will wait for the complete data, including the distribution of treatment doses in the two groups, after the trial is peer-reviewed and published. Wegovy is the only obesity drug to reduce the risk of heart attack or stroke, noted the manufacturer. 

The FDA approved Wegovy as a treatment for heart disease in March, while Zepbound is expected to get the green light as a treatment for obstructive sleep apnea.

Novo Nordisk, meanwhile, is banking on a novel drug with a dual mode of action, CagriSema, to regain an edge on efficacy over Lilly. Its late-stage trial results, which Novo projected could likely result in 25% weight loss, are expected this year.