Notes: PSI-7977 is a prodrug form of the nucleoside analog and RNA-dependent RNA polymerase (RdRp) inhibitor PSI-7411.{25066} It is converted to PSI-7411 by cathepsin A and carboxylesterase 1 (CES1) via the intermediate PSI-352707. PSI-7977 inhibits hepatitis C virus (HCV) replication in an HCV replicon assay (EC50 = 0.092 µM). It also inhibits the replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in human brain cortical organoids derived from induced pluripotent stem cells (iPSCs) when used at a concentration of 20 µM.{62921} Formulations containing PSI-7977 have been used in the treatment of HCV infections.