Sections of the FDA’s Drug Quality and Security Act (DQSA) distinguish compounding pharmacies (503A) from outsourcing facilities (503B). Due to several factors, many of which are related to drug shortages and the USP 797/USP 800 updates, 503A pharmacies are considering partnering with 503B entities for compounded sterile preparations and/or hazardous materials. We’ll discuss the differences between 503A pharmacies and 503B outsourcing facilities, review Section 503B and summarize how to effectively evaluate 503B compounding pharmacies for a potential partnership.