Established pharmaceutical products often have complex supply chains and regulatory histories. In Europe the European Directorate for the Quality of Medicine (EDQM) (information from European Pharmacopoeia website, http://www.pheur.org/) have promoted the use of certificates of suitability of the European Pharmacopoeia to ensure the quality of medicines by a commonly recognised set of standards, allowing the free movement of medicinal products in member states. This contribution describes the analytical and synthetic chemistry required to synthesise the impurities of manufacture of clobetasone butyrate.