People are turning themselves into lab rats': the injectable peptides craze sweeping the US Well actually The Guardian FDA Warning Letter to Neil R. Feins, M.D. 2009 05 20 Circare 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 Heard about BPC 157 in health and wellness products? Think it's a "miracle" peptide? Think again. Claims about BPC 157 are based on lab or animal studies, NOT human clinical studies.