503A vs 503B Compounding: What the Difference Means
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[Glossary · Quality, storage and rules]

503A vs 503B

Also called 503A pharmacy, 503B outsourcing facility, outsourcing facility · Reviewed

Definition: 503A and 503B are two sections of US drug law that set the rules for compounding. A 503A pharmacy compounds for an identified patient with a valid prescription. A 503B outsourcing facility registers with FDA, follows factory-level manufacturing rules and may compound with or without prescriptions for individual patients.

Side by side

503A pharmacy vs 503B outsourcing facility
503A pharmacy503B outsourcing facility
WhoLicensed pharmacist in a state-licensed pharmacy, or a licensed physicianA facility at one address that compounds sterile drugs and elects to register
PrescriptionNeeded for an identified individual patientMay or may not have prescriptions for identified patients
Manufacturing rulesNot held to CGMPMust follow CGMP (current good manufacturing practice)
FDA inspectionSurveillance and for-cause inspectionsInspected on a risk-based schedule
FDA approved product?NoNo

Sources: 21 USC 353a and 353b, and FDA compounding pages. CGMP (current good manufacturing practice) is the quality rule set that drug factories follow. 503B facilities must also report adverse events and send FDA a list of the drugs they made every 6 months.

Why it matters when you track doses

A 503B label must say "This is a compounded drug" or a similar statement. Neither type of product is FDA approved, so label data for the brand-name drug do not carry over, including storage times and beyond-use dates.

When you switch pharmacies, the vial concentration may change. Treat every new source as a new vial and check its strength before your first dose from it.

Common mix-ups

  • "FDA registered" is not "FDA approved." A 503B facility is registered with and inspected by FDA, but the drugs it makes are still not FDA approved.
  • Neither is a research seller. Products labeled research use only fall under neither section.

Read more on Dose Track: Peptide storage guides

General education drawn from labels and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your product are the final word.
Compounding pharmacyA compounding pharmacy makes a medicine from raw ingredients for a specific patient, rather than… Beyond-use date (BUD)A beyond-use date (BUD) is the date after which a compounded or opened medicine should not be used. It is… Research use only (RUO)Research use only (RUO) is a label phrase. In US rules it comes from labeling for in vitro diagnostic… Certificate of analysis (COA)A certificate of analysis (COA) is a document listing test results for one batch (lot) of a product: what…

Frequently asked questions

Is a 503B facility better than a 503A pharmacy?+
A 503B facility is held to CGMP and inspected by FDA on a risk-based schedule, which are stricter quality rules. Neither makes FDA-approved drugs.
How often do 503B facilities report to FDA?+
They report adverse events and send FDA a list of the drugs they compounded every six months, in June and December.
Does a 503B facility need a prescription?+
Not always. Federal law says an outsourcing facility may or may not obtain prescriptions for identified individual patients.

Sources

  1. 21 USC 353a: pharmacy compounding (section 503A), Cornell LII
  2. 21 USC 353b: outsourcing facilities (section 503B), Cornell LII
  3. FDA: Compounding and the FDA, questions and answers
  4. FDA: Human drug compounding laws (sections 503A and 503B)
  5. FDA: Information for outsourcing facilities

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