"Same active ingredient": what FDA warning letters allege about compounded GLP-1 sellers
Year: 2026
Type: preprint
Abstract: After the US shortages of semaglutide and tirzepatide ended in 2024–2025, the Food and Drug Administration (FDA) turned to warning letters to police compounded and unapproved versions. I analysed every letter returned by full-text searches of FDA's public warning-letter index for these drugs and related terms. The searches, run on 21 October 2026, returned 163 letters; 154 met inclusion criteria after excluding five letters to the brand-name manufacturers and four in which the drugs were incidental. Each letter was coded twice, by an AI-written rule-based coder and by an AI reading pass, against a written codebook; median Cohen's κ across 22 codes was 0.93, and disagreements were adjudicated by re-reading. The letters were issued in bursts: 110 (71%) were dated on three days, 9 September 2025, 20 February 2026 and 8 June 2026. Letters to the 109 telehealth platforms, clinics and med spas all cited false or misleading advertising of compounded drugs; FDA cited claims of sameness with a branded drug (for example, "same active ingredient as") in 75 of them and, from February 2026, labels presenting the seller as the compounder (51 letters). Letters to online pharmacies, research-peptide sellers, compounders and API suppliers instead alleged unapproved new drugs, sale without a prescription, CGMP and sterility failures, and retatrutide or other unapproved incretins (16 of these letters; 22 letters overall). Letter counts describe FDA's enforcement choices, not the size or behaviour of the market, and every finding is an FDA allegation rather than an adjudicated violation. Preprint, not peer reviewed. Also published at https://x9m8.com/same-active-ingredient-fda-warning-letters/. The zip file contains the code, results and the two independent audits.
Author: Kalafatis, Peter
Language: English
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7224463757