Eli Lilly’s LLY.N powerful weight-loss drug Zepbound hit 77,590 new prescriptions in the U.S. for the week ending March 8, surpassing Novo Nordisk’s NOVOb.CO rival obesity medicine Wegovy for the first time since it was launched, according to data from IQVIA.

Some 6,000 fewer Wegovy prescriptions were filled in the United States that week, but Novo maintained its lead for total weekly prescriptions over Zepbound by 25,307, according to the data published by JPMorgan in a weekly note.

Novo, Lilly and IQVIA IQV.N did not immediately respond to requests for comment.

Lilly launched Zepbound in the U.S. in December, more than two years after Wegovy’s approval in June 2021.

Shares of Lilly and Novo were off about 1% and 2%, respectively on a down day for the broader market.

At stake in the competition for new patients looking to lose weight is a market analysts’ see reaching at least $100 billion by the end of the decade. Demand so far has well outpaced supplies, as consumers flock to new treatments that have been shown to reduce weight by as much as 20%.

Zepbound and Wegovy belong to a class of drugs called GLP-1 agonists developed for type 2 diabetes that also reduce food cravings and cause the stomach to empty more slowly.

Data analytics firm GlobalData in a report on Friday said GLP-1 drugs are on pace to this year surpass widely used cancer immunotherapies as the best-selling medicines, driven by trial data showing they can also treat other health conditions, and a surge in celebrity and influencer endorsements. Merck and Co’s MRK.N cancer drug Keytruda is currently the world’s top-selling prescription medicine with over $25 billion in annual sales.

The U.S. Food and Drug Administration last week approved Wegovy for lowering the risk of stroke and heart attack in overweight or obese adults who do not have diabetes.

GlobalData forecast the market for these medicines reaching $105 billion by 2029, and that Novo Nordisk would capture more than half of that with its portfolio of GLP-1 drugs, including Wegovy.

The Danish drugmaker last week said it was confident it would launch a pill version of its experimental weight-loss drug amycretin this decade. Currently GLP-1 drugs are injected.

Lilly’s diabetes drug Mounjaro, which has the same active ingredient as Zepbound, will be the top-selling GLP-1 with $33.4 billion in annual sales by 2029, GlobalData forecast.

Lilly this week said it has partnered with Amazon.com’s AMZN.O pharmacy unit to deliver drug prescriptions sent to its direct-to-consumer service LillyDirect, including those for Zepbound.

Frank Cunningham, an executive at Lilly, said the company was “very pleased” with the number of prescriptions it had filled through LillyDirect so far.

(Reporting by Patrick Wingrove in New YorkEditing by Bill Berkrot)