Compounding explained
503A and 503B.
What’s the difference?
Two frameworks for compounding.
Different requirements.
These names refer to sections of the Federal Food, Drug, and Cosmetic Act. Each sets conditions for certain exemptions that apply to compounded medicines. [1]
See the comparisonPatient-specific
prescriptions
Compounding for an identified individual patient.
Registered
outsourcing facilities
May supply healthcare facilities without patient-specific prescriptions.
At a glance
How the requirements differ.
The comparison below highlights key distinctions. Both frameworks have additional conditions. [2]
| Requirement | 503A | 503B |
|---|---|---|
| Who compounds? | A licensed pharmacist in a state-licensed pharmacy or federal facility, or a licensed physician. | An FDA-registered outsourcing facility, with compounding by or under the direct supervision of a licensed pharmacist. |
| Patient-specific prescription | Based on a valid prescription for an identified patient. Limited anticipatory compounding is permitted under specified conditions. | May compound with or without patient-specific prescriptions, including for healthcare-facility stock. |
| Manufacturing requirements | Exempt from current good manufacturing practice (CGMP) requirements when all 503A conditions are met. | Subject to CGMP requirements. |
| Primary oversight | State boards generally oversee state-licensed pharmacies day to day. FDA also has inspection and enforcement authority. | Primarily FDA oversight, with inspections on a risk-based schedule. |
Oversight summary: FDA’s compounding questions and answers. Other federal requirements, including rules against insanitary conditions, apply in both settings.
For patients and practices
What the distinction
means in practice.
A patient’s prescription or a facility’s supply
503A centers on individual prescriptions. A 503B outsourcing facility can also supply a hospital or clinic for office stock. That does not make prescription medicines available to patients without a prescription. [3]
Compounding and FDA approval are different
Compounded drugs are not FDA-approved. FDA does not review each compounded medicine for safety, effectiveness or quality before marketing. A facility’s registration does not give its products FDA approval. [4]
Start with the clinical need
FDA recommends compounded medicines only when a patient’s medical needs cannot be met by an FDA-approved drug. Discuss the need with your clinician, then confirm the specific preparation with the pharmacy. [4]
Using this guide
Common questions.
Does 503B mean a facility is FDA-approved?
No. FDA registration is not product approval or a guarantee of compliance. FDA’s registered outsourcing facilities list includes registration, inspection and related information.
Can a 503B facility fill patient-specific prescriptions?
Yes. Outsourcing facilities may obtain prescriptions for individual patients, but patient-specific prescriptions are not required for all of their compounding. See FDA’s comparison.
Does the framework determine whether a drug is available?
The framework alone does not establish availability. Ask the pharmacy about the specific preparation, prescription requirements and destination before arranging an order.
Sources & further reading
- FDA: Human Drug Compounding Laws
- FDA: FD&C Act Provisions That Apply to Human Drug Compounding
- FDA: Prescription Requirement Under Section 503A (PDF)
- FDA: Compounding Questions and Answers
This overview does not cover every federal or state requirement. Refer to current requirements and your care team for a specific situation.