Bernstein: US GLP-1 weekly prescriptions rebound as competition in oral drugs accelerates

Weekly prescriptions rebound: how strong is the growth trend?

In the week ended 23 October, total US GLP-1 prescriptions increased by 77.3 thousand week over week to 2.89 million, a rise of 2.7%; all six major brands posted weekly growth, with Zepbound contributing the largest increase of 33.8 thousand prescriptions.
The smoother four-week data slowed: combined prescriptions for semaglutide, tirzepatide and orforglipron rose 0.9% from the previous four weeks, down from 1.6% previously; rolling four-week year-over-year growth fell from 37.7% to 37.0%.

Among total branded prescriptions for the three ingredients above, Lilly's share rose 0.07 percentage points week over week to 64.1%. Share gains for Zepbound and Foundayo offset a decline for Mounjaro.
Total Zepbound prescriptions rose 4.2% week over week to 839.1 thousand, with the increase coming mainly from vials and KwikPen, up 16.7 thousand and 14.4 thousand prescriptions, respectively. Bernstein noted that KwikPen is one of the dosage forms offered under Medicare's obesity reimbursement program, and its new prescriptions increased markedly after reimbursement began on 1 July.
Although total Mounjaro prescriptions rose 1.3% week over week to 877.9 thousand, its share fell 0.46 percentage points to 31.6%; its rolling four-week year-over-year growth also fell from 31.1% to 29.6%.

In its 29th week on the market, Foundayo's total prescriptions rose 8.8% week over week to 63.1 thousand; in its 42nd week, Wegovy Pill rose 5.7% to 183 thousand.
New-to-brand prescriptions measure patients who have not used the brand in the past 12 months, including both first-time users of the drug class and those switching or adding a drug. During the week, such prescriptions for Foundayo rose 4.8% to 20.2 thousand, while Wegovy Pill rose 9.2% to 34.1 thousand.
Of combined new-to-brand prescriptions for the two oral weight-loss drugs, Foundayo's share fell 0.96 percentage points week over week to 37.2%, while Wegovy Pill accounted for 62.8%. Lilly's overall share of new-to-brand prescriptions also fell 0.24 percentage points to 58.6%, contrasting with its rising share of total prescriptions.
The proportion of Foundayo's total prescriptions accounted for by continuing prescriptions recently fell to 67%, below Wegovy Pill's 72%; Bernstein believes this partly reflects faster growth in new-to-brand prescriptions, while the absolute number of continuing prescriptions continues to grow in line with the trend.

Based on information from Lilly's earnings call, Bernstein continues to believe oral GLP-1 drugs could expand the market. The firm expects Foundayo's rollout to take months: it is a novel molecule requiring more physician education, and direct-to-consumer advertising cannot be fully rolled out until physician education is sufficiently advanced.
IQVIA prescription data has different coverage levels for the two oral drugs. Lilly's investor relations team says Foundayo's overall capture rate is currently about 90%; Novo Nordisk says Wegovy Pill's capture rate to date is only about 50%. This coverage difference therefore needs to be considered when comparing their IQVIA prescription volumes.