Antiviral guanosine ribonucleoside analog; misincorporated into mRNA by viral-dependent RNA polymerases. Binds to and redistributes mammalian eIF4E from the nucleus to the cytoplasm (Ki ~ 0.3 μM for the active metabolite, ribavirin triphosphate). Represses colony formation of primary AML-M5 progenitor cells (IC50 ~ 1 μM); reduces disease severity in acute myeloid leukemia (AML). Orally available. Purity 99%. MW (observed): 244.2