Glossary
503A pharmacy: a conditional exemption, not a class of licence
"503A" names a conditional exemption in federal law, not a licence anybody issues. Section 503A of the Federal Food, Drug, and Cosmetic Act, codified at 21 U.S.C. § 353a, suspends three federal requirements for a compounded drug product — but only where the preparation was compounded for an identified individual patient on a valid prescription order, by a licensed pharmacist in a state-licensed pharmacy or by a licensed physician. The pharmacy itself is licensed by a state board of pharmacy. There is no federal application, no federal approval and no federal register of these pharmacies, which is exactly why diligence on one has to run through the state board and the accreditor instead.
An exemption attached to a preparation
The section does not create a category of business. It names federal requirements that stop applying, and the conditions on which they stop:
is by (A) a licensed pharmacist in a State licensed pharmacy or a Federal facility, or (B) a licensed physician, on the prescription order for such individual patient made by a licensed physician or other licensed practitioner authorized by State law to prescribe drugs
Two consequences follow immediately. The licence in that sentence is a state one — the statute says "State licensed pharmacy" in its own words. And the exemption is conditioned on the patient-specific prescription, which means it reaches individual preparations rather than attaching to the pharmacy as a standing status.
What the exemption covers
FDA describes the same three provisions in plainer terms than the statute does:
Section 503A describes the conditions under which compounded human drug products are exempt from the FD&C Act sections on FDA approval prior to marketing, current good manufacturing practice (CGMP) requirements, and labeling with adequate directions for use.
The middle item is the one most often reported backwards. Compounding under this section is exempt from cGMP, and it buys that exemption with the prescription condition. The other pathway makes the opposite trade, which is set out in 503A vs 503B.
Note also what the exemption is not: an exemption from the new-drug approval requirement is the reason no compounded preparation is ever approved, a point worked through in why a compounded drug is never FDA-approved.
Why there is no federal list to check
FDA publishes a register of facilities registered under the other section, updated with each facility’s last inspection date and whether an action followed. No equivalent federal table exists for pharmacies operating under this one. They are licensed and inspected by states, so the records that answer a question about them sit with a state board of pharmacy — including the non-resident credential the pharmacy needs in the state it ships into — and, separately, with an accreditor such as PCAB.
That asymmetry decides how a prescriber checks one. The sequence, and which record answers which question, is set out in how to vet a compounding pharmacy; the board lookup portals are collected in the reference tables. The credential a supplier needs where you practise is defined at non-resident pharmacy licence, and the quality standard it works to is a separate axis again: USP <795> and <797>.