Eli Lilly joins FDA's side in tirzepatide compounding lawsuit

Eli Lilly joined the lawsuit over compounded tirzepatide in January 2025 as an intervenor, siding with the U.S. Food and Drug Administration against compounding pharmacies that had sued to keep making cheaper, unapproved versions of Mounjaro and Zepbound ^[2]. Lilly makes those brand-name tirzepatide products ^[2].

The case, Outsourcing Facilities Association v. FDA, was filed in the U.S. District Court for the Northern District of Texas after the FDA took tirzepatide off its drug shortage list ^[1][2]. The FDA first declared the shortage over on Oct. 2, 2024, then reversed course three weeks later after the Outsourcing Facilities Association sued and public pressure mounted, and reaffirmed the delisting in December 2024 ^[2]. The Outsourcing Facilities Association and Farmakeio Custom Compounding argued the agency should have used formal notice-and-comment rulemaking and that its shortage determination was arbitrary and capricious ^[2].

After the delisting, the FDA set discretionary periods for compounders to adjust: one that ended Feb. 18, 2025, for 503A compounding pharmacies and one that ended March 19, 2025, for 503B outsourcing facilities. During those windows the FDA said it did not intend to take action against compounders for violations of the Food, Drug, and Cosmetic Act based on tirzepatide's earlier presence on the shortage list ^[1]. An attempt to win a preliminary injunction staying the FDA's shortage determination failed in March 2025 ^[1]. On May 7, 2025, the district court upheld the FDA's decision to remove two tirzepatide injection products from the shortage list, finding the agency acted within its statutory authority and that the plaintiffs had not shown enough harm to warrant judicial intervention ^[1].

That ruling was later affirmed on appeal. On Aug. 27, the 5th U.S. Circuit Court of Appeals held that the FDA acted lawfully when it declared Lilly's tirzepatide shortage resolved ^[2]. The panel rejected both of the compounders' arguments, finding they had actual notice and a real chance to weigh in because the FDA's reevaluation period ran nearly 60 days, double the Administrative Procedure Act's standard comment window, so any procedural misstep was harmless. On the merits, the panel said the FDA reasonably relied on Lilly's supply data, which showed an 11.6 million-dose surplus by November 2024 after about $23 billion in manufacturing investment, over less reliable evidence such as wholesaler screenshots and patient surveys ^[2].

Why it matters for patients

Because the FDA now considers tirzepatide available, compounding pharmacies, outsourcing facilities and health care providers can no longer rely on the shortage-list exception to compound "essentially copies" of tirzepatide injections. They must also make sure their products are not substantially the same as, or administered by the same route as, commercially available products ^[1]. The May 7 decision effectively clears the way for increased enforcement against noncompliant compounding practices, and compounders no longer have the general protection from FDA enforcement that was available during the discretionary periods ^[1].

Several practical questions have not been reported. It has not been disclosed what will happen to patients now using compounded tirzepatide, whether existing supplies will continue to be filled, or how costs might change for people who switch products. The FDA separately told pharmacies in April 2026 to stop compounding GLP-1s once brand versions clear the shortage list, and Lilly has raised safety concerns about compounded tirzepatide-B12 products, claims the Alliance for Pharmacy Compounding has disputed ^[2].

What happens next

A parallel case over Novo Nordisk's semaglutide products, filed in February 2025, is pending before the same panel ^[2]. No ruling date in that case has been reported, and it has not been disclosed whether either side will ask the Supreme Court to review the tirzepatide decision. The FDA has also removed semaglutide from its shortage data, which the agency's actions suggest may signal an end to the national shortage of certain GLP-1 medications ^[1]. Whether further enforcement actions follow against specific compounders has not been reported.