Indications
Famciclovir is primarily indicated for the treatment of acute herpes zoster, commonly known as shingles. Additionally, it is used for both treatment and suppression of recurrent genital herpes in patients with a competent immune system. It also serves as a treatment option for recurrent mucocutaneous herpes simplex infections in individuals living with HIV.
Pharmacodynamics
Famciclovir functions as a prodrug, which means that it undergoes rapid conversion into its active form, penciclovir, once inside the body. Penciclovir is an antiviral agent that demonstrates inhibitory effects on herpes simplex virus types 1 (HSV-1) and 2 (HSV-2), as well as the varicella zoster virus (VZV). This activity effectively inhibits the synthesis and replication of herpes viral DNA.
Absorption
Upon administration, famciclovir exhibits an absorption rate of approximately 77%.
Metabolism
Famciclovir undergoes metabolic processing within the liver, where it is transformed into its active metabolite, penciclovir. This hepatic metabolism is a key step in activating famciclovir's antiviral properties and enables it to combat viral infections effectively.
Mechanism of Action
Famciclovir, following oral administration, is swiftly converted into its active form, penciclovir. This active metabolite exhibits potent antiviral properties, particularly against herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), as well as varicella-zoster virus (VZV). Within cells infected by these viruses, viral thymidine kinase catalyzes the phosphorylation of penciclovir to its monophosphate form. Subsequently, cellular kinases further phosphorylate it to form penciclovir triphosphate. In vitro studies have shown that penciclovir triphosphate effectively inhibits HSV-2 DNA polymerase through competitive interaction with deoxyguanosine triphosphate. As a result, the synthesis and replication of viral DNA are selectively hindered, curtailing the proliferation of the herpesvirus.
