About famciclovirnucleosides and nucleotides :a synthetic acyclic guanine analogue , antiviral for hsv, varicella-zoster.mechanism of action of famciclovirfamciclovir is a prodrug and it is converted to active penciclovir. it undergoes phosphorylation in the presence thymidine kinase and form penciclovir monophosphate and it is again phosphorylated by cellular kinase and form penciclovir triphosphate. this penciclovir triphosphate inhibits dna polymerase enzyme and inhibits dna synthesis and consequently inhibit viral replication.indications for famciclovir1.herpes simplex virus infection 2.herpes zoster and genital herpes infections in immunocompromised patients interactions for famcicloviruricosurics: probenicid possibly reduces famciclovir excretion thereby increasing plasma concentration.