Compounded medication
A preparation made by a pharmacy rather than manufactured under an FDA approval. Legal, long-established, and operating under a different set of requirements than an approved drug.
Compounding is a pharmacy combining or altering ingredients to produce a medication for a patient. It exists because approved products do not cover every case: a patient who needs a dose that is not manufactured, a formulation without an allergen, a liquid where only tablets exist, or a drug in shortage.
A compounded preparation is not an FDA-approved drug. That is not an accusation, it is the category. Approval attaches to a specific product made by a specific manufacturer under a specific process, and a compounded preparation is made to order.
503A and 503B are different things
Two sections of the Federal Food, Drug, and Cosmetic Act define two different kinds of compounder, and the distinction decides almost everything about oversight.
503A is the traditional pharmacy. It compounds for an identified patient against a prescription. It is regulated primarily by the state board of pharmacy, and it is not required to follow CGMP, the manufacturing standard that applies to drug manufacturers. It may not compound at commercial scale for general distribution.
503B is an outsourcing facility. It registers with the FDA, is required to comply with CGMP, is subject to FDA inspection, and may produce batches without a prescription for an individual patient, typically supplying clinics and hospitals.
So "compounded" spans a pharmacy operating under state oversight without CGMP, and a federally registered facility inspected against the manufacturing standard. Those are meaningfully different assurances and the word does not distinguish them. It is a fair question to ask which one filled a prescription.
What compounding does not include
Whichever section applies, several things that come with an approved drug are absent.
- No approval for an indication. No regulator has reviewed evidence that this preparation works for the use it is prescribed for.
- No approved labelling. There is no prescribing information carrying trial-derived dosing, contraindications and interactions.
- Batch-to-batch variation is a live concern, particularly at 503A where CGMP does not apply.
- Testing requirements differ by section and by state, rather than being uniform.
The bulks list, and why it decides what exists
A 503A pharmacy may only compound from bulk drug substances that are permitted. The FDA maintains categories for substances nominated for that list. Category 1 substances may be used while under evaluation. Category 2 substances may not, because the agency identified significant safety risks.
This is the mechanism that determines whether a given peptide is available through a pharmacy at all. BPC-157 was placed in Category 2 in September 2023, which is why it has circulated as a research chemical rather than as a compounded preparation.
In July 2026 the Pharmacy Compounding Advisory Committee recommended six peptides for the list, including BPC-157, against its own reviewers' recommendation and by one and two-vote margins. Those recommendations are not rules and the rulemaking has not happened. We wrote up that meeting and what it does and does not change in the PCAC vote piece.
The shortage exception, and what happened when it closed
The clearest recent illustration of how conditional this all is came from the GLP-1 drugs.
When a drug is on the FDA's official shortage list, compounders may prepare copies of it, which they otherwise may not do for a commercially available approved product. Semaglutide and tirzepatide were both listed during their shortages, and a large compounding market grew up around that allowance.
When the FDA declared the shortages resolved, the allowance went with them. The basis for compounding those drugs was the shortage, so removing the shortage removed the basis, and the compounded versions had to wind down on the agency's timeline.
The point for anyone reading a compounded product page: availability through a compounding pharmacy can be a temporary regulatory condition rather than a settled fact. It is worth knowing which of those you are looking at, because one of them ends without notice.
Related terms: research chemical, off-label, FDA approval, certificate of analysis.
