FDA Puts BPC 157, TB 500, and 5 Other Peptides Under the Microscope: What Prescribers Need to Know About the 503A Review Lengea RFK Jr. & claimed regenerative peptides like BPC 157 The Niche 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 RFK Jr. & claimed regenerative peptides like BPC 157 The Niche FDA to weigh easing limits on unproven peptides favored by RFK Jr. and MAHA supporters PBS News