Lilly and Novo Nordisk open a new Lanham Act front against compounders' 503B claims

Eli Lilly and Novo Nordisk, the makers of branded GLP-1 drugs, are opening a new legal front against compounding pharmacies that sell copycat versions of semaglutide and tirzepatide. Instead of arguing that a compounded product itself is illegal, the companies are attacking a narrower and easier-to-prove target: false statements compounders make about whether their own facilities meet federal 503B outsourcing rules ^[1][2].

A federal court in South Carolina gave this approach a boost on August 6, 2026, in a case that did not involve GLP-1 drugs but set a legal precedent that applies to them. In Pacira BioSciences v. Nephron Sterile Compounding, the court ruled that a compounder's claim of "503B" compliance can be checked as a plain fact, not dismissed as mere opinion, because the rule is "clear on its face" and can be verified by consulting FDA lists ^[2]. The court found that Nephron falsely labeled one of its compounded pain drugs, RKK, as a "503B Product" because the drug itself, not just its individual ingredients, needed to appear on an FDA shortage list to qualify ^[2]. A consumer survey showed that 14.8% of people who saw Nephron's marketing believed the product was 503B-compliant, evidence the court said was ordinarily enough to prove the claim was misleading ^[2].

Lilly and Novo have already built a wide legal campaign against copycat sellers. Novo has filed 130 federal lawsuits and five challenges before the National Advertising Division (NAD), an industry self-regulatory body, while Lilly has filed dozens of lawsuits and at least five NAD cases ^[1]. The NAD forum is faster and cheaper than court, putting the burden on the compounder to justify its claims within months, though participation is voluntary and the group has no legal authority of its own ^[1]. Recent NAD cases pressured Noom to drop a tagline about its compounded GLP-1 dosing and pushed Willow Health Services to permanently stop certain safety and efficacy claims about its compounded semaglutide ^[1].

The financial stakes are large. Lilly's tirzepatide franchise, sold as Mounjaro and Zepbound, reached $40 billion in sales, and Novo's semaglutide products, sold as Ozempic, Wegovy, and Rybelsus, generated $35 billion last year ^[1]. The FDA has also sent more than 100 warning letters to companies over misbranded compounded-drug claims in the past year, though those letters have focused narrowly on issues like active ingredients and branding ^[1].

Why it matters for patients

This legal strategy does not decide whether a specific compounded semaglutide or tirzepatide product is safe or lawful to take. It targets what a pharmacy says about its own regulatory status, not the drug's quality ^[1][2]. That means a favorable ruling for Lilly or Novo could stop a company from claiming "503B compliant" status without settling the separate question of whether the underlying compounded product meets safety standards.

For patients using compounded GLP-1 products, this could mean more marketing claims get pulled or changed, but it does not automatically clarify which compounders are operating within the law. Attorneys tracking the space say FDA enforcement so far has stayed narrow, focused on what ads should not say rather than offering guidance on what accurate claims should look like ^[1].

What happens next

Legal experts expect Lilly and Novo to keep combining NAD challenges, which can resolve in months, with slower federal Lanham Act lawsuits modeled on the Pacira precedent ^[1][2]. Whether this specific legal theory will be applied in a GLP-1 case, and how compounders will respond, is not yet known from the available reporting.