US FDA proposes curbs on mass compounding of Novo, Lilly's weight-loss drugs

April 30 (Reuters) - The U.S. Food and Drug Administration on Thursday proposed excluding Novo Nordisk and Eli Lilly's weight-loss drugs from a key compounding list, potentially limiting large-scale production by outsourcing facilities.

If finalized, the move could impact telehealth firms that rely on outsourcing facilities to produce these drugs in bulk, while bolstering Novo and Lilly's efforts against unauthorized versions that are eating into sales of their blockbuster treatments.

U.S.-listed shares of Novo rose nearly 6%, while Lilly gained nearly 10% in afternoon trading.

The regulator said on Thursday it found no clinical need for outsourcing facilities to compound semaglutide, the active ingredient of Novo's Wegovy and Ozempic, and tirzepatide, sold as Zepbound and Mounjaro by Lilly, from bulk drug substances.

The proposal also includes Novo's older molecule liraglutide.

A Lilly spokesperson said the company is "pleased" with the FDA's confirmation there is no clinical need for compounded tirzepatide.

"That means there is no basis for compounders to make tirzepatide knockoffs. Lilly will continue working to protect patients from the risks associated with unapproved drugs prescribed without a medical need."

"Novo Nordisk applauds FDA's thorough scientific analysis and conclusion that there is no medical basis or clinical need for the continued mass compounding of unapproved semaglutide and liraglutide drugs," a spokesperson for the company told Reuters.

Compounding, in which pharmacies mix ingredients for specialized medicines or to copy a drug but at different dosages, has flourished as Americans chase more affordable options. It is legal in certain circumstances, such as a drug shortage or when prescribed by a physician to address patient side-effects.

The FDA was reviewing nominations for the so-called 503B bulks list, which identifies drug ingredients that outsourcing facilities may use in compounding.

Section 503B of the Federal Food, Drug, and Cosmetic Act allows FDA-regulated outsourcing facilities to produce compounded medicines in bulk for healthcare providers, often without patient-specific prescriptions. Section 503A allows state‑licensed physicians and pharmacists to compound medicines for individual patients under state oversight.

Many telehealth firms, including Hims & Hers, offer compounded medicines tailored to individual patients through 503A pharmacies, while also relying on 503B outsourcing facilities to produce them at scale.

The FDA has invited public comment on the proposal until June 29, before the agency issues its final decision.

(Reporting by Mrinalika Roy and Mariam Sunny in Bengaluru; Editing by Leroy Leo and Shilpi Majumdar)

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This story was originally published April 30, 2026 at 10:29 AM.