On September 18, 2026 the FDA sent a warning letter to Empower Clinic Services, which does business as Empower Pharmacy, one of the biggest names in compounded weight-loss medicine. The products at issue were tirzepatide combined with niacinamide and semaglutide combined with cyanocobalamin, a form of vitamin B12.
Under section 503A of the Food, Drug and Cosmetic Act, a compounding pharmacy may not make what is "essentially a copy" of a commercially available FDA-approved drug. Compounders have long argued that adding an ingredient creates a clinically different product and takes it outside that rule. The agency's answer in this letter was that niacinamide and cyanocobalamin did not create a real clinical difference, so the products remained copies.
The sentence that matters
The letter then went further than the usual recitation. The agency wrote that the volume of products Empower was producing suggested that the "differences between products you are compounding and the FDA-approved products are pretextual." Pretextual is a lawyer's word. It means the stated reason is not the real reason. It is the first time the agency has used it in a GLP-1 warning letter, and it changes the character of the argument from whether a given formula is different enough to whether the whole practice is a workaround.
Three concerns were flagged: production volume, templated language asserting a significant clinical difference across many prescriptions, and gaps in the documentation of aseptic processing and environmental monitoring.
The door was already closing
This letter did not arrive on its own. On April 30, 2026 the agency proposed a rule that would formally remove semaglutide, tirzepatide and liraglutide from the list of bulk substances that 503B outsourcing facilities are allowed to compound from. If finalized, the rule shuts the bulk-compounding route for those three drugs entirely for outsourcing facilities, regardless of shortage. The public comment period closed on June 29. The agency cited more than 455 adverse event reports tied to compounded semaglutide and more than 320 tied to compounded tirzepatide. FDA Commissioner Marty Makary put the position plainly: outsourcing facilities "cannot lawfully compound using bulk drug substances unless there is a clear clinical need."
Section 503A pharmacies, the smaller patient-specific compounders, were left with narrow exceptions: a documented allergy to an excipient in the approved product, or a dose strength the manufacturer does not make. The Empower letter is the agency reading those exceptions tightly.
What fills the gap
The compounding lane supplied most of the telehealth weight-loss boom of 2024 and 2025. Both ends of it are now being closed, by rule for outsourcing facilities and by enforcement for the pharmacies that stayed in the business after the shortages ended.
Demand did not go anywhere. A September 25 review in the American Journal of Managed Care cited projections of a gray market in these and other peptides reaching $50 to $75 billion by 2028, and quoted a clinician who put it bluntly: "Banning demand won't eliminate demand. It's pushing patients towards shadier places." The same review reported clinician accounts of products that contained only a fraction of what their labels stated.
That is the environment the warning letters of late August and this one in September were written into. One set of letters told online sellers that a research label does not make a drug a non-drug. This one told a pharmacy that a vitamin does not make a copy a non-copy. The agency is closing the easy arguments first.
Sources: FDA warning letter to Empower Clinic Services, LLC, September 18, 2026; FDA proposed rule and statement of April 30, 2026; Pharmacy Times, May 1, 2026; Frier Levitt analysis, September 25, 2026; American Journal of Managed Care, September 25, 2026.
For research use only · Not for human or veterinary use · No compound discussed here is FDA-approved for any indication