Used to treat recurrent cold sores on the lips and face from various herpesvirus invections.
Penciclovir is the active metabolite of the oral product famciclovir. The more favorable results observed with topical penciclovir versus topical acyclovir for the treatment of herpes labialis may be due to the longer intracellular half-life of penciclovir in HSV-infected cells. The activated drug inhibits the viral DNA polymerase. This impairs the ability of the virus to replicate within the cell.
Mechanism of action
Penciclovir has <i>in vitro</i> 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. The monophosphate form of the drug is then converted to penciclovir triphosphate by cellular kinases. The intracellular triphosphate of penciclovir is retained <i>in vitro</i> inside HSV-infected cells for 10-20 hours, compared with 0.7-1 hour for acyclovir. <i>in vitro</i> studies show that penciclovir triphosphate selectively inhibits viral DNA polymerase by competing with deoxyguanosine triphosphate. Inhibition of DNA synthesis of virus-infected cells inhibits viral replication. In cells not infected with HSV, DNA synthesis is unaltered. Resistant mutants of HSV can occur from qualitative changes in viral thymidine kinase or DNA polymerase. The most commonly encountered acyclovir-resistant mutants that are deficient in viral thymidine kinase are also resistant to penciclovir.
Route of administration
Antiinfectives for Systemic Use
Antivirals for Systemic Use
Chemical Actions and Uses
Direct Acting Antivirals
Heterocyclic Compounds, 2-Ring
Nucleosides and Nucleotides Excl. Reverse Transcriptase Inhibitors
Drug Info/Drug Targets: DrugBank 3.0: a comprehensive resource for 'omics' research on drugs. Knox C, Law V, Jewison
T, Liu P, Ly S, Frolkis A, Pon A, Banco K, Mak C, Neveu V, Djoumbou Y, Eisner R, Guo AC, Wishart DS.
Nucleic Acids Res. 2011 Jan; 39 (Database issue):D1035-41. | PMID:21059682