Self-Assembly Properties of an Amphiphilic Phosphate Ester Prodrug Designed for the Treatment of COVID-19

•A comprehensive demonstration of how to characterize and understand the self-assembly behavior of amphiphilic molecules in solution-based parenteral drug products, including CMC determination by DOSY NMR.•An innovative use of computational tools and multiple orthogonal experimental techniques to inform robust drug product design, contribute to impurity control strategies and help enable rapid progression of an anti-infective parenteral drug product to the clinic.•A case study of lipophilic impurity solubilization by prodrug self-assembly that informs when impurities might precipitate, leading to undesired particulate matter formation, for example during dose administration or on stability.