Penciclovir is an acyclic analogue of 2'-deoxyguanosine.
Penciclovir has activity against herpesviruses and hepatitis B virus.
Penciclovir is converted to its triphosphate form (penciclovir triphosphate), which selectively inhibits viral DNA polymerase by competing with deoxyguanosine triphosphate.
The primary mechanism of resistance to penciclovir is related to viral thymidine kinase and DNA polymerase mutations.
No relationship has been established between the effective in vitro and in vivo concentrations of penciclovir.
Oral penciclovir is poorly absorbed, with an oral bioavailability of 5%. Penciclovir has a large volume of distribution (112 L, or 1.5 L/kg) suggesting that it is widely distributed into tissues. It is <20% bound to plasma proteins over the concentration range of 0.1 to 20 mcg/mL. Renal excretion is the major route of elimination.
The most common adverse effects are mild erythema and headache.
Apply cream to cold sore every 2 hours during waking periods for 4 days.
Penciclovir should only be used on herpes labialis on the lips and face.
There are documented clinically significant drug interactions with penciclovir.
Category B: No evidence of risk in humans but studies inadequate.
DenavirŪ/Novartis Consumer Health Inc