The FDA has designated 503B compounding pharmacies as those with outsourcing facilities that may manufacture large batches with or without prescriptions to be sold to healthcare facilities. The FDA requires compounders to share the products with them every 6 months in rears, last registry date 2019-2
Often drugs are not in thier necessary or final form that is needed for a patient. In those cases often drugs need to be compounded and one option for compounding is working with a 503b compounder.
Compounded drugs are not FDA-approved. This means that FDA does not verify the safety or effectiveness of compounded drugs.
Compounded drugs can serve an important medical need for patients, but they do not have the same safety, quality, and effectiveness assurances as approved drugs. Unnecessary use of compounded drugs unnecessarily exposes patients to potentially serious health risks.
The quality requirements for compounded drugs varies based on setting. 503B compounders are subject to CGMP (current good manufacturing processes) requirement. While 503A compounded drugs are exempt from CGMP requirements. For example, let's say you wanted to what drug warning letters were recently issued. You can see the recent FDA warning letters here.