The FDA and Compounded GLP-1s: Where the Lines Keep Moving
The regulatory landscape surrounding compounded semaglutide and tirzepatide has shifted more times in the past two years than most researchers can track. What began as a straightforward drug shortage issue has evolved into a complex legal, scientific, and public health debate involving the FDA, compounding pharmacies, pharmaceutical manufacturers, and millions of patients caught in the middle.
Understanding where the lines currently stand — and why they keep moving — requires examining the intersection of shortage law, compounding regulations, and the unprecedented demand for GLP-1 receptor agonists.
The Shortage That Started It All
The entire compounded GLP-1 market exists because of a legal mechanism most people had never heard of before 2022: the FDA's drug shortage list. Under Section 503A and 503B of the Federal Food, Drug, and Cosmetic Act, compounding pharmacies can produce copies of FDA-approved drugs when those drugs appear on the official shortage list.
Semaglutide was added to the FDA's shortage list in March 2022, and tirzepatide followed in December 2022. The shortages were driven by explosive demand after clinical trials demonstrated remarkable efficacy for weight loss — Wilding et al., 2021 reported 14.9% mean body weight reduction with semaglutide 2.4 mg in the landmark STEP 1 trial, while Jastreboff et al., 2022 showed tirzepatide achieving up to 22.5% weight loss at the highest dose.
Novo Nordisk and Eli Lilly simply could not manufacture enough product to meet demand. Compounding pharmacies stepped into the gap, and a multi-billion-dollar parallel market emerged almost overnight.
The Legal Framework: 503A vs. 503B
Not all compounding pharmacies operate under the same rules, and this distinction has become central to the regulatory debate.
503A pharmacies compound medications based on individual patient prescriptions. They are primarily regulated by state boards of pharmacy and must adhere to United States Pharmacopeia (USP) standards. 503B outsourcing facilities, created by the Drug Quality and Security Act of 2013, operate more like small manufacturers — they can produce larger batches without patient-specific prescriptions but must register with the FDA and comply with current good manufacturing practice (cGMP) requirements.
The FDA has historically treated these two categories differently in enforcement actions. 503B facilities face more direct FDA oversight, including regular inspections documented in the FDA's outsourcing facility inspection database. This distinction matters enormously as enforcement actions ramp up.
The Tirzepatide Shortage Resolution — And Its Fallout
In October 2024, the FDA announced that tirzepatide had been removed from the shortage list, stating that Eli Lilly could now meet demand for all approved dose presentations. This triggered an immediate legal battle, as the removal meant compounding pharmacies would need to cease production.
The Outsourcing Facilities Association (OFA) filed a lawsuit challenging the FDA's determination, arguing the agency's process was opaque and that real-world access issues persisted. A federal court initially granted a temporary restraining order, allowing some compounders to continue producing tirzepatide while the case proceeded.
The back-and-forth continued into early 2025. The FDA maintained its position while acknowledging the complexity of the situation. Eli Lilly, for its part, launched legal actions against specific compounding pharmacies and medspas it alleged were selling products that were misbranded or contained impurities.
Semaglutide's Parallel Path
Semaglutide's regulatory trajectory followed a similar but not identical pattern. As of early 2025, certain dose forms of semaglutide remained on the shortage list while others were resolved. The FDA's shortage determinations are made on a dose-by-dose and formulation-by-formulation basis, which creates a patchwork of legal and illegal compounding activity that is difficult for pharmacies, prescribers, and patients to navigate.
Novo Nordisk has been expanding manufacturing capacity aggressively, investing billions in new production facilities in Denmark, France, and the United States. The company has publicly stated its goal of resolving all shortage designations, which would effectively close the compounding window.
Research continues to validate the underlying molecules. The SELECT cardiovascular outcomes trial (Lincoff et al., 2023) demonstrated that semaglutide 2.4 mg reduced major adverse cardiovascular events by 20% in adults with obesity and established cardiovascular disease — findings that further intensified demand.
Quality and Safety Concerns
The FDA's regulatory posture is not purely about protecting pharmaceutical market exclusivity. The agency has raised legitimate safety concerns about compounded GLP-1 products.
In January 2024, the FDA issued a safety alert warning consumers about adverse events reported with compounded semaglutide, including dosing errors and products containing semaglutide sodium salt rather than the base form used in approved products. The salt form has a different molecular weight, meaning a milligram-for-milligram dose is not equivalent — a critical distinction that could lead to under- or over-dosing.
A 2024 analysis by the FDA found that some compounded products failed sterility and potency testing. Of particular concern were:
However, proponents of compounding counter that well-run 503B facilities operating under cGMP produce high-quality products, and that the failures cited by the FDA represent bad actors rather than systemic problems. The Professional Compounding Centers of America (PCCA) has advocated for distinguishing between compliant and non-compliant pharmacies rather than restricting compounding broadly.
The Patent and Exclusivity Dimension
Underlying the shortage debate is a deeper question about intellectual property. Novo Nordisk and Eli Lilly hold extensive patent portfolios on their respective molecules, formulations, delivery devices, and manufacturing processes.
Under normal circumstances, compounding copies of patented, commercially available drugs exists in a legal gray area. The shortage designation provided legal cover, but its removal exposes compounders to potential patent infringement claims in addition to FDA enforcement.
Eli Lilly has been particularly aggressive, arguing that tirzepatide compounding constitutes infringement of patents that extend well beyond the active ingredient itself. The outcome of these cases will likely shape the compounding industry's relationship with branded pharmaceuticals for years to come.
What Researchers Should Watch
Several developments will determine where the regulatory lines settle:
The broader scientific context also matters. Upcoming oral formulations of semaglutide at higher doses (Knop et al., 202301185-6)) and next-generation multi-agonists like retatrutide (Jastreboff et al., 2023) could eventually ease supply pressure by diversifying available treatment options.