PENCICLOVIR IS A NUCLEOSIDE ANALOGUE STRUCTURALLY RELATED TO GUANINE, WHICH IS ACTIVE AGAINST HERPES VIRUSES.FOR SYSTEMIC USE, PENCICLOVIR IS GIVEN ORALLY AS THE PRODRUG FAMCICLOVIR INTRAVENOUS ADMINISTRATION OF PENCICLOVIR HAS BEEN INVESTIGATED.
PENCICLOVIR HAS IN VITRO INHIBITORY ACTIVITY AGAINST HERPES SIMPLEX VIRUS TYPES 1 (HSV-1) AND 2 (HSV-2). IN CELLS INFECTED WITH HSV-1 OR HSV-2, VIRAL THYMIDINE KINASE PHOSPHORYLATES PENCICLOVIR TO A MONOPHOSPHATE FORM WHICH, IN TURN, IS CONVERTED TO PENCICLOVIR TRIPHOSPHATE BY CELLULAR KINASES. IN VITRO STUDIES DEMONSTRATE THAT PENCICLOVIR TRIPHOSPHATE INHIBITS HSV POLYMERASE COMPETITIVELY WITH DEOXYGUANOSINE TRIPHOSPHATE. CONSEQUENTLY, HERPES VIRAL DNA SYNTHESIS AND, THEREFORE, REPLICATION ARE SELECTIVELY INHIBITED.