503A vs 503B Compounding
Where the two categories come from
Both categories are defined in the Federal Food, Drug, and Cosmetic Act, as amended by the Drug Quality and Security Act of 2013. That Act was passed following the 2012 fungal meningitis outbreak traced to contaminated compounded injections, and it created a clear split between compounding for an individual patient and compounding at production scale.
The distinction is not a label a facility chooses for marketing. It determines which rules apply, who inspects, and what the facility is permitted to make.
503A — traditional compounding pharmacies
A 503A pharmacy compounds a medication for an identified individual patient, based on a prescription or a documented history of receiving them. Compounding may be done by a licensed pharmacist or licensed physician.
Oversight sits primarily with the state board of pharmacy. A 503A pharmacy is exempt from FDA new-drug-approval, adequate-directions-for-use, and current Good Manufacturing Practice requirements, provided it stays within the conditions of section 503A.
It cannot compound in bulk for general distribution to other facilities. That is the boundary that separates it from an outsourcing facility.
503B — outsourcing facilities
A 503B outsourcing facility registers with the FDA voluntarily. Once registered, it may compound sterile preparations in bulk without patient-specific prescriptions and supply them to healthcare facilities.
In exchange, it must comply with current Good Manufacturing Practice, is subject to FDA inspection on a risk-based schedule, and reports adverse events and its product list to the FDA. Many also hold a state licence or permit in the states they ship to.
FDA publishes the register of outsourcing facilities. Registration is not an FDA approval or endorsement of the products a facility makes.
The USP chapters that apply
USP <795> covers non-sterile compounding — creams, ointments, capsules, oral liquids. It sets expectations for ingredients, procedures, documentation and beyond-use dating.
USP <797> covers sterile compounding — injections, ophthalmics, and other preparations that must be sterile. It governs facility design and air quality, personnel training and garbing, environmental monitoring, and beyond-use dating.
USP <800> covers handling hazardous drugs, including many chemotherapy agents, and applies wherever hazardous drugs are received, stored, compounded or disposed of — not only in compounding areas.
How each chapter is enforced varies: states adopt USP standards into their own rules on their own timelines, so the operative requirement is the state rule as much as the chapter itself.
What this means for pharmacy staffing
The two settings need different competencies. Sterile compounding under USP <797> requires documented aseptic technique training, garbing competency, and periodic media-fill testing — a specific, evidenced skill set rather than general pharmacy experience.
USP <800> adds hazardous-drug handling competencies on top, which is why oncology and infusion settings screen for it separately.
A 503B facility operating under cGMP also carries documentation and quality-system expectations closer to pharmaceutical manufacturing than to a retail pharmacy, which changes what prior experience is relevant.
Common questions
What is a 503A pharmacy?
A 503A pharmacy is a traditional compounding pharmacy. It compounds for an identified individual patient against a prescription, is overseen primarily by its state board of pharmacy, and is exempt from FDA current Good Manufacturing Practice requirements provided it stays within the conditions of section 503A.
What is a 503B outsourcing facility?
A 503B outsourcing facility registers with the FDA and may compound sterile preparations in bulk without patient-specific prescriptions. It must comply with current Good Manufacturing Practice and is subject to FDA inspection. Registration is not an FDA approval of its products.
What is the difference between 503A and 503B?
The core difference is whether compounding is tied to an individual prescription. A 503A pharmacy compounds for a specific patient and answers primarily to its state board. A 503B facility compounds in bulk without patient-specific prescriptions, registers with the FDA, and must meet current Good Manufacturing Practice.
Does a compounding pharmacy have to register with the FDA?
A 503A pharmacy does not register with the FDA as an outsourcing facility; it is licensed by its state board of pharmacy. Registering as a 503B outsourcing facility is voluntary, but a facility that wants to compound in bulk without patient-specific prescriptions needs that registration.
What is the difference between USP 795, 797 and 800?
USP <795> covers non-sterile compounding, USP <797> covers sterile compounding, and USP <800> covers handling hazardous drugs anywhere they are received, stored, compounded or disposed of. A facility can be subject to more than one at the same time.
What extra training do sterile compounding staff need?
Sterile compounding under USP <797> generally requires documented aseptic technique training, garbing and hand-hygiene competency, and periodic media-fill testing. Where hazardous drugs are handled, USP <800> adds further competency and handling requirements.