Compounding
Definition
Preparing a customised medicine by combining or altering ingredients, done by a licensed pharmacy or an outsourcing facility. Compounded drugs are not FDA-approved and are not reviewed for safety, effectiveness or quality before they are supplied.
Where this term comes up
Entries whose definition mentions Compounding.
What this means for research sourcing
Regulatory status varies by jurisdiction and applies to research supply, not human use. Volta sells to researchers only.
Related Terms in Regulatory
Compounded Medication
A preparation made up by a licensed pharmacy for a specific patient's requirements. It sits under a different regulatory regime from a manufactured drug, with different expectations about testing, labelling and shelf life.
503A Pharmacy
A compounding pharmacy operating under section 503A of the Federal Food, Drug, and Cosmetic Act, which exempts it from pre-market approval and cGMP provided it compounds against a patient-specific prescription. Oversight is by the state board of pharmacy.
503B Outsourcing Facility
A compounder registered under section 503B, added by the Drug Quality and Security Act in 2013. Unlike a 503A pharmacy it must follow cGMP, is inspected by the FDA on a risk basis, reports adverse events, and may supply without a patient-specific prescription.
Bulk Drug Substance
The active pharmaceutical ingredient used as a starting material in compounding. Under 503A it may be used only if it meets a USP or NF monograph, is a component of an approved drug, or appears on the FDA's 503A bulks list, and it must arrive with a certificate from a registered manufacturer.
FDA Category 1
In the FDA's review of substances nominated for compounding, the list of those evaluated and found eligible for use as bulk drug substances by 503A and 503B compounders.
FDA Category 2
The list of nominated substances the FDA has flagged with significant safety risks, which are therefore not eligible for compounding while the nomination stands. BPC-157 was placed in this category.
PCAC (Pharmacy Compounding Advisory Committee)
The FDA advisory committee that reviews substances nominated for the compounding bulks lists, weighing the physicochemical characterisation, safety data and historical use before recommending for or against inclusion under 503A and 503B.
Drug Shortage Declaration
An FDA finding that a drug is in shortage, which temporarily widens what compounders may prepare. The semaglutide shortage was declared resolved in February 2025 and tirzepatide in October 2024, which closed that allowance for both.