Skip to the reading [American Peptide Supply](/) Four chapters on the supply picture - [01 The change](/#the-change) - [02 The history](/#the-history) - [03 Who does what](/#who-does-what) - [04 Keeping care](/#keeping-care) A U.S. supply guide · Read on 27 October 2026 # 503A and 503B give compounders different jobs The numbers name two sections of federal drug law. Here’s what they mean for the explanation you’re given. ## Two sections of law, two sets of duties 503A and 503B sound like filing labels. They’re sections of the Federal Food, Drug, and Cosmetic Act, and they help explain who is responsible for a compounded medicine. Compounding means making or changing a medicine for a medical need. FDA’s [compounding explanation](https://www.fda.gov/drugs/human-drug-compounding/compounding-and-fda-questions-and-answers) makes a key distinction: a compounded drug is not FDA-approved. Neither number changes that. ### Compounded medicine An approved generic and a compounded preparation aren’t the same thing. Compounding does not carry FDA approval. ## 503A centers on one person’s prescription FDA’s [prescription guidance](https://www.fda.gov/regulatory-information/search-fda-guidance-documents/prescription-requirement-under-section-503a-federal-food-drug-and-cosmetic-act-guidance-industry) covers this framework. A licensed pharmacist in a state-licensed pharmacy or federal facility, or a licensed physician, can compound when the legal conditions are met. Limited preparation ahead of expected prescriptions is allowed. But the [full guidance requires a valid patient-specific prescription before distribution](https://www.fda.gov/media/97347/download). That means a prescription for an identified person, rather than a general plan to supply a group. The useful question for your care is why this preparation fits your needs. An old shortage announcement can’t answer that for you. ### Individual means individual The clinician’s explanation needs to concern the person receiving care. A general statement about supply can’t do that job. ## 503B puts more duties on the facility An outsourcing facility compounds sterile (germ-free) medicines in batches and chooses to register with FDA. It need not be a licensed pharmacy or obtain individual prescriptions. It must follow [federal manufacturing rules, inspections and reporting requirements](https://www.fda.gov/drugs/human-drug-compounding/information-outsourcing-facilities). FDA’s [registration explanation](https://www.fda.gov/drugs/human-drug-compounding/questions-and-answers-outsourcing-facility-registration) is clear: registration alone proves neither compliance nor drug approval. “Registered” is one piece of information, not a quality verdict. [State boards generally oversee ordinary pharmacies day to day](https://www.fda.gov/drugs/human-drug-compounding/compounding-and-fda-questions-and-answers); FDA primarily oversees outsourcing facilities. The two frameworks assign different duties rather than a simple better-or-worse ranking. ### Manufacturing rules Current good manufacturing practice means federal drug-manufacturing quality rules. 503A preparations are exempt from those rules when conditions are met; other safety duties remain. ## After the shortage, the reason still matters FDA’s [1 April 2026 update](https://www.fda.gov/drugs/drug-alerts-and-statements/fda-clarifies-policies-compounders-national-glp-1-supply-begins-stabilize) said neither semaglutide nor tirzepatide was on the shortage list or the 503B bulks list of allowed raw ingredients. So 503B facilities couldn’t compound them from those raw ingredients. Under 503A, a pharmacist or physician can’t make what is essentially a copy of a commercially available drug regularly or in excessive amounts. A changed preparation falls outside that copy definition when the prescriber determines and documents that the change makes a significant difference for the named patient. The other legal conditions still apply. Safety matters under either section. FDA warns that [contamination or the wrong amount of active ingredient can cause serious harm](https://www.fda.gov/drugs/human-drug-compounding/understanding-risks-compounded-drugs). A supply problem doesn’t make those risks smaller. ## Sources for this reading - [Compounding and the FDA: Questions and Answers](https://www.fda.gov/drugs/human-drug-compounding/compounding-and-fda-questions-and-answers) - [Prescription Requirement Under Section 503A — guidance overview](https://www.fda.gov/regulatory-information/search-fda-guidance-documents/prescription-requirement-under-section-503a-federal-food-drug-and-cosmetic-act-guidance-industry) - [Prescription Requirement Under Section 503A — full guidance](https://www.fda.gov/media/97347/download) - [Information for Outsourcing Facilities](https://www.fda.gov/drugs/human-drug-compounding/information-outsourcing-facilities) - [Questions and Answers: Outsourcing Facility Registration](https://www.fda.gov/drugs/human-drug-compounding/questions-and-answers-outsourcing-facility-registration) - [FDA’s shortage and compounding timeline](https://www.fda.gov/drugs/drug-alerts-and-statements/fda-clarifies-policies-compounders-national-glp-1-supply-begins-stabilize) - [Understanding the Risks of Compounded Drugs](https://www.fda.gov/drugs/human-drug-compounding/understanding-risks-compounded-drugs) Read on 27 October 2026. [All readings and their context](/references). [Bring the responsibilities back to the care plan](/care-continuity) We follow the supply calendar as a guide; we are neither a clinic nor a pharmacy, and we sell nothing. [References](/references) [About](/about) [Contact](/contact) © 2026 American Peptide Supply