Sorivudine

Sorivudine is a nucleoside analog. After entering cells infected with varicella-zoster virus, sorivudine is first phosphorylated by the viral thymidine kinase and then converted by host kinases into its active triphosphate form. It is subsequently mistaken by the viral DNA polymerase as dTTP and incorporated into viral DNA, thereby inhibiting viral DNA synthesis. Because sorivudine is metabolized into bromovinyluracil, it irreversibly inhibits dihydropyrimidine dehydrogenase. If it is used together with certain drugs that require dihydropyrimidine dehydrogenase for metabolism, there may be a risk of fatal toxicity due to excessive drug accumulation in the body.