[CAS NO. 39809-25-1]  Penciclovir

Penciclovir is a guanine analogue antiviral drug used for the treatment of various herpesvirus infections. It is a nucleoside analogue which exhibits low toxicity and good selectivity. Penciclovir is a selective antiherpesvirus agent, particularly against herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) and varicella-zoster virus (VZV). Penciclovir is converted to its active form, penciclovir triphosphate, by cellular kinases. It inhibits viral DNA polymerase by competing with deoxyguanosine triphosphate. It inhibits DNA synthesis of virus-infected cells. Penciclovir has in vitro activity against herpes simplex virus types 1 (HSV-1) and 2 (HSV-2). It does not inhibit DNA synthesis in non-infected cells. Mode of resistance is via qualitative changes in viral thymidine kinase or DNA polymerase. Penciclovir has activity against several herpes viruses with IC50 of 37.9 μM for HHV-6A and 77.8 μM for HHV-6B. Herpes simplex virus-1 studies indicate that Penciclovir induces apoptosis without causing much genotoxicity.