from Klaus Klumpp and Mark Smith writing in Hepatitis C: Antiviral Drug Discovery and Development:
Nucleoside analogs have transformed our ability to treat viral diseases and have contributed to a significant reduction in morbidity, mortality and suffering worldwide caused by viral infections, including Human Immunodeficiency Virus (HIV), Hepatitis B Virus and Herpes Virus infections. Similarly, nucleoside analogs hold great promise to also become the backbone of the future standard of care for the treatment of Hepatitis C Virus infection, because the currently available data suggest that nucleoside analogs can provide high antiviral potency, a high barrier to resistance selection, antiviral potency across the whole spectrum of Hepatitis C Virus genotypes and favorable properties for combination with other antiviral agents. This chapter summarizes efforts in antiviral research that have led to the discovery of Valopicitabine (NM283), Balapiravir (R1626) and R7128 (RG7128). Current efforts aim to further improve efficacy by optimizing nucleoside intrinsic potency, phosphorylation efficiency and delivery of antiviral nucleoside analogs.
Further reading: Hepatitis C: Antiviral Drug Discovery and Development