Zepbound overtakes Wegovy in new US prescriptions for first time

Zepbound logged 77,590 new US prescriptions in the week that ended March 8, overtaking Wegovy in new starts for the first time since Eli Lilly's obesity medicine reached the market, according to IQVIA data published by JPMorgan in a weekly note ^[1].

Wegovy's count was about 6,000 lower that week. Novo Nordisk's drug still held a lead of 25,307 when refills are included, a category where it remained ahead ^[1].

The shift in the weekly tally came with Zepbound on the US market only since December, while Wegovy has been approved since June 2021 ^[1]. Novo, Lilly and IQVIA did not immediately respond to requests for comment, and the companies have not said what moved the numbers ^[1].

Both products are GLP-1 agonists, a class first developed for type 2 diabetes that also blunts food cravings and slows the rate at which the stomach empties ^[1]. Zepbound's active ingredient is tirzepatide, also sold as Mounjaro for diabetes; Wegovy is semaglutide ^[1]. Trials have shown weight loss of up to 20% ^[1]. Reuters reported that demand for these medicines has run well ahead of supply ^[1].

Analysts put the eventual market at no less than $100 billion by the end of the decade ^[1]. GlobalData, in a report dated the same day as the prescription figures, projected $105 billion in sales by 2029, with Novo taking more than half of that through its GLP-1 portfolio including Wegovy. The firm expects Mounjaro to lead all GLP-1 products at $33.4 billion a year by 2029 ^[1].

GlobalData also said this class is on track to outsell widely used cancer immunotherapies during the year, helped by trial results in other conditions and heavy celebrity and influencer promotion. Merck's Keytruda, at more than $25 billion in yearly sales, is currently the top-selling prescription medicine worldwide ^[1].

A week before the data, the FDA cleared Wegovy to reduce the risk of heart attack and stroke in overweight or obese adults who do not have diabetes ^[1]. Lilly, meanwhile, said it partnered with Amazon's pharmacy business to ship prescriptions routed through its LillyDirect consumer service, Zepbound included; executive Frank Cunningham said the company was "very pleased" with the volume filled so far, without giving a number ^[1]. Novo has said it is confident of launching a pill form of its experimental obesity drug amycretin within this decade; GLP-1 medicines today are injections ^[1]. Shares of Lilly slipped about 1% and Novo about 2% on a weaker day for the wider market ^[1].

Why it matters for patients

Two companies are now trading the lead in new weight-loss starts week by week. How quickly either can fill a prescription, or whether a particular pharmacy has the product on hand, has not been disclosed, and demand has been running ahead of supply ^[1].

Coverage could also shift. Wegovy's new heart-risk indication widens the group of patients it is cleared for, and insurers often look to FDA labeling when writing rules, but whether plans will cover the added use has not been reported ^[1]. Delivery channels are changing too: Lilly's arrangement with Amazon is aimed at sending prescriptions straight to patients through LillyDirect ^[1].

Both options now available remain injectable. A pill version of Novo's amycretin is in development, and the company says it expects to launch it this decade ^[1].

What happens next

GlobalData's projections extend to 2029, when it expects the GLP-1 category to reach $105 billion and Mounjaro to be the single biggest seller at $33.4 billion a year ^[1]. Novo has not given a date for an amycretin pill beyond saying it expects one this decade ^[1]. No timetable has been disclosed for when supply of Wegovy or Zepbound might match demand ^[1].