503A Vs. 503B Compounding Pharmacies: Similarities & Differences Last week @fda sends out clarification on who can and cannot compound #glp1 like #tirzeaptide and #semaglutide and this week ProRx 503b shuts down GLP 1 compounding while @martymakary is photographed holding bootleg # 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 Peptide Reclassification 2026: What Researchers Want 503A vs. 503B Epicur Pharma