Table 3.

Basic description of key differences between 503a and 503b compounding pharmacies relevant to this study.^a

Basic comparison of 503a vs 503b compounding pharmacies
	503a	503b
Regulatory supervision	State Boards of Pharmacy	US Food and Drug Administration
Who do they compound for?	Individual prescriptions for individual Patients	Both individual prescriptions and large batches of product which can be distributed to healthcare facilities
Ship products across state lines?	No (<5% of sales must be across state lines)	Yes

^aSeveral caveats and further key regulatory differences exist but are outside the scope of this discussion.