The last couple of years we see a trend of health authorities (HAs) across the globe increasingly raising questions on the control strategy of active pharmaceutical ingredients (APIs) when reviewing Drug Master files (DMFs, including CEP DMFs) or drug substance sections (3.2.S). Based on ICH Q11 and related guidance, HAs are expecting more information on how API manufacturers control and maintain the quality of their APIs, from development throughout the lifecycle. In this whitepaper, we will explain more about control strategies for APIs.