Distinguishing between compounding facilities and the development of the 503B bulk drug substance list.

The purpose of this commentary is to describe the differences between 503A and 503B facilities and the policies and restrictions for compounding from bulk drug substances. Due to the 2012 meningitis outbreak linked to compounded steroid injections, the landscape of pharmacy compounding was changed in the United States. This event led to the creation of two distinct types of compounding pharmacies, 503A and 503B facilities. 503B facilities are restricted from compounding using bulk drug substances unless they are on the Food and Drug Administration drug shortage list or appear on the 503B Bulk Drug Substance list. This commentary hopes to bring more attention to the development of the 503B Bulk Drug Substance list being developed by the FDA and to encourage practitioners and pharmacists to provide insight into the drug substances nominated for the list.