Zepbound tops Wegovy in weekly new US prescriptions for the first time

Zepbound, Eli Lilly's tirzepatide obesity medicine, recorded 77,590 new U.S. prescriptions in the week ending March 8, 2024, moving ahead of Novo Nordisk's Wegovy for the first time since Zepbound reached the market ^[1]. The counts come from IQVIA data published by JPMorgan in a weekly note and were reported on March 15, 2024 ^[1].

The margin was narrow. Wegovy filled roughly 6,000 fewer prescriptions than Zepbound during that week, yet Novo's semaglutide product remained ahead when all weekly prescriptions are counted, leading Zepbound by 25,307 fills ^[1]. Novo, Lilly and IQVIA did not immediately respond to requests for comment ^[1].

Timing helps explain the shift. Lilly brought Zepbound to the U.S. market in December 2023, roughly two and a half years after Wegovy's June 2021 approval ^[1]. Both drugs belong to the GLP-1 agonist class, first developed for type 2 diabetes; they also dampen food cravings and slow how quickly the stomach empties ^[1]. Drugs in the class have produced weight loss of as much as 20%, and demand has run well ahead of supply ^[1]. Zepbound contains the same active ingredient as Lilly's diabetes drug Mounjaro ^[1].

Broader market estimates arrived alongside the prescription figures. GlobalData said in a report that GLP-1 medicines are on track this year to overtake widely used cancer immunotherapies as the best-selling drugs, pointing to trial results showing they can treat other conditions and to a wave of endorsements from celebrities and influencers ^[1]. Merck's Keytruda, the current top-selling prescription medicine, brings in more than $25 billion in yearly sales ^[1]. GlobalData projected a $105 billion market for these medicines by 2029, with Novo capturing more than half through its GLP-1 portfolio, and named Mounjaro the top-selling GLP-1 at $33.4 billion in annual sales by 2029 ^[1]. Analysts see the weight-loss market reaching at least $100 billion by the end of the decade ^[1]. Lilly shares slipped about 1% and Novo shares about 2% on a down day for the wider market ^[1].

Two other developments landed near the prescription report. Lilly said it had teamed up with Amazon.com's pharmacy business to deliver prescriptions routed through its direct-to-consumer service LillyDirect, including Zepbound orders; Lilly executive Frank Cunningham said the company was "very pleased" with how many prescriptions had been filled that way ^[1]. And the U.S. Food and Drug Administration approved Wegovy for lowering the risk of stroke and heart attack in overweight or obese adults who do not have diabetes ^[1].

Why it matters for patients

Prescriptions that are new measure starts, not the total number of people on a drug. By that measure Zepbound took the lead for one week, while Wegovy kept a 25,307-prescription advantage across all weekly fills ^[1].

The IQVIA figures say nothing about price, insurance coverage or how the two drugs compare in effectiveness, and none of that is addressed in the data ^[1]. The count covers a single week, so it does not show whether patients stayed on treatment or switched between products. Both drugs sit in the same class, and both have faced demand beyond available supply ^[1].

What happens next

Novo said it expects to launch a pill version of its experimental weight-loss drug amycretin within this decade; GLP-1 medicines are currently given by injection ^[1]. GlobalData's forecast puts the category at $105 billion by 2029 ^[1]. Whether Zepbound's advantage in new prescriptions carried into the weeks after March 8 has not been reported ^[1].