DOJ says: "compounding pharmacies, which are an increasing focus of enforcement efforts. Ensuring compliance by compounding pharmacies has been—and will continue to be—a major enforcement priority for both the Branch and FDA. Several years ago, Congress clarified and strengthened the FDCA’s applicability to compounding pharmacies in the wake of the tragedy at the New England Compounding Center. The FDCA recognizes two types of drug compounders: 503A pharmacies (so-called traditional compounders), which compound drugs on a per-prescription basis, and 503B outsourcing facilities, who may compound large quantities of drugs. FDA has made it a priority to develop the regulatory framework under the FDCA for drug compounding and to strengthen its oversight of drug compounders."

quoted from https://www.justice.gov/opa/speech/deputy-assistant-attorney-general-james-m-burnham-delivers-remarks-2018-food-and-drug-law