503A vs 503B: A Sourcing Review Guide
This guide is available to read here without submitting a form. It helps clinic and pharmacy buyers prepare questions for their qualified reviewers; it does not establish that a particular product can be supplied.
503A: review the prescription and substance requirements
Section 503A generally addresses qualifying compounding by state-licensed pharmacies or physicians for identified patients, subject to statutory conditions. Bulk-substance requirements are one part of that framework. Start with the 503A eligibility review; a supplier’s channel label does not replace a documented decision.
503B: review the facility and the preparation
A registered outsourcing facility may compound without patient-specific prescriptions when applicable conditions are satisfied. Registration does not mean FDA approval of its drugs or blanket permission to compound every substance. Evaluate the exact preparation, bulk-substance restrictions, essentially-copy restrictions and receiving jurisdiction.
Document the actual transaction
Record whether the proposal is for a patient-specific prescription, office inventory or bulk material for a pharmacy. Identify the purchaser, compounder, intended destination and responsible reviewer. Do not treat those transaction types as interchangeable simply because a supplier offers the same product name in multiple categories.
Collect the evidence before ordering
Request source identity, the product presentation, applicable eligibility rationale, lot documentation, storage instructions and written commercial terms. Log unresolved questions and the professional responsible for approval. Use the chain-of-custody checklist for incoming API evidence.
Find the appropriate purchasing guide
Continue to clinic sourcing requirements or pharmacy sourcing requirements. For more discussion of the framework, read what clinic buyers need to verify. Those pages do not confirm live stock or product eligibility.
Sources and limits
FDA: section 503A bulk substances and FDA: section 503B bulk substances. Check current federal guidance and applicable state requirements with qualified reviewers. This guide is educational, not medical or legal advice.