FDA Set to Review Peptide Access for Compounding Pharmacies Drug Topics The reason peptide access is changing comes down to two regulatory categories most patients don't know exist: 503A and 503B. 503A = traditional compounding pharmacies. State licensed, patient specific prescriptions. 503B = FDA registered outsourcing KLOW Blend 80mg Koi Peptides FDA Removes 12 Peptides from 503A Category 2 : r us_pharmacies Restoring Balance: What the FDA's Peptide Announcement Could Mean for Patient Access and Safety Empower Pharmacy of the Federal Food, Drug, and Cosmetic Act (FDCA).*