The FDA has issued warning letters to multiple companies marketing compounded Retatrutide, an investigational drug from Eli Lilly still in Phase II trials. While early studies have shown promising weight loss results, Retatrutide Sources: U.S. Food and Drug Administration (FDA) Compounding and the FDA (503A & 503B guidance) FDA warning letters on unapproved peptide products National Institutes of Health (NIH) PubMed The U.S. Food and Drug Administration is moving toward allowing compounding pharmacies to produce more than a dozen injectable peptides that were banned because of potentially significant safety risks, the New York FDA Warning Letter to Neil R. Feins, M.D. 2009 05 20 Circare FDA Sends 30 Warning Letters To Continue Clampdown on Compounded GLP 1s BioSpace Is BPC 157 Legal? Understanding Its Status and Implications