Famciclovir: An overview
- Kimon C Zachary, MD
Kimon C Zachary, MD
- Assistant Professor of Medicine
- Harvard Medical School
Famciclovir is an oral prodrug that is converted by first-pass metabolism to the antiviral drug penciclovir [1,2].
MECHANISM OF ACTION
Penciclovir, upon intracellular uptake, is monophosphorylated by virally-encoded thymidine kinase and subsequently converted to a triphosphate by cellular enzymes. Penciclovir triphosphate preferentially inhibits the DNA polymerase of susceptible viruses; at clinically relevant levels, there is no substantial effect upon cellular DNA polymerase, thereby minimizing side effects to the host .
This mechanism is similar to that described for acyclovir; however, compared with acyclovir triphosphate, penciclovir triphosphate has a lower affinity for viral DNA polymerase but a longer intracellular half-life . (See "Acyclovir: An overview".)
Spectrum of activity — Penciclovir is active against herpes simplex virus (HSV) types 1 and 2, and varicella zoster virus (VZV). Epstein-Barr virus is also susceptible in vitro .
Mechanism of resistance — The mechanisms of resistance to penciclovir are similar to those described for acyclovir . Three mechanisms have been shown to endow herpes simplex viruses with resistance to acyclovir, a phenomenon rare in the immunocompetent host :To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information on subscription options, click below on the option that best describes you:
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