penciclovir

Penciclovir is a synthetic acyclic guanine nucleoside analogue antiviral drug used topically for the treatment of herpes simplex virus (HSV) infections, primarily herpes labialis (cold sores). It acts as a nucleoside analogue that is selectively activated in virally infected cells by viral thymidine kinase, which phosphorylates penciclovir to its monophosphate form. Cellular kinases then convert it to penciclovir triphosphate, the active metabolite. This active form competitively inhibits viral DNA polymerase, thereby blocking viral DNA synthesis and replication with minimal effect on uninfected cells. Penciclovir exhibits low toxicity and high selectivity due to preferential activation in infected cells and higher affinity for viral versus human DNA polymerases. The drug is poorly absorbed orally and thus formulated as a topical cream for external use on lips and face[3][5][6]. It does not cure herpes infections but reduces pain, discomfort, and healing time when applied early in the course of infection[1][2].

Brand names

Denavir

Other names

9-(4-hydroxy-3-hydroxymethylbut-1-yl)guanine