The difference between a 503A pharmacy and a 503B pharmacy lies in their regulatory status, scope of compounding, and prescription requirements under the Drug Quality and Security Act (DQSA).
A 503A pharmacy is a traditional compounding pharmacy regulated primarily by state boards of pharmacy. It is permitted to compound medications only pursuant to a valid, patient-specific prescription. These pharmacies are exempt from certain FDA requirements, such as current Good Manufacturing Practice (cGMP) standards, but must comply with United States Pharmacopeia (USP) standards and state regulations. 503A pharmacies cannot compound for office use or in bulk for distribution; each compounded medication must be tied to an individual patient prescription.[1-2]
A 503B pharmacy, also known as an outsourcing facility, is registered with the FDA and subject to cGMP requirements. 503B facilities can compound large batches of medications without patient-specific prescriptions, allowing them to supply hospitals, clinics, and other healthcare providers for office use. However, they are restricted from compounding with bulk drug substances unless those substances are on the FDA drug shortage list or the 503B Bulk Drug Substance list. 503B pharmacies are inspected by the FDA and play a key role in addressing drug shortages and providing ready-to-use compounded products for healthcare institutions.[3-5]
In summary, 503A pharmacies compound only for individual patients based on prescriptions and are state-regulated, while 503B pharmacies (outsourcing facilities) can compound in bulk for office use, are FDA-registered, and must comply with cGMP standards.[1][3-5]