When a new medicine is approved, there is under a 25% chance that the United States Food and Drug Administration (FDA) or the European Medicines Agency (EMA) will impose, as part of conditional approval, studies conducted to satisfy postmarketing requirements. US regulations governing such studies are found in the 2011 guidance document regarding “Postmarketing Studies and Clinical Trials — Implementation of Section 505(o)(3) of the Federal Food, Drug, and Cosmetic Act (1).” EMA regulations are found in the 2017 “Guideline…