Penciclovir (DenavirŪ)

Class:

Penciclovir is an acyclic analogue of 2'-deoxyguanosine.

Antiviral Activity:

Penciclovir has activity against herpesviruses and hepatitis B virus.

Mechanism of Action:

Penciclovir is converted to its triphosphate form (penciclovir triphosphate), which selectively inhibits viral DNA polymerase by competing with deoxyguanosine triphosphate.

Mechanism of Resistance:

The primary mechanism of resistance to penciclovir is related to viral thymidine kinase and DNA polymerase mutations.

Pharmacodynamics:

No relationship has been established between the effective in vitro and in vivo concentrations of penciclovir.

Pharmacokinetics:

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.

Adverse Effects:

The most common adverse effects are mild erythema and headache.

Dosage:

Cream 1%

Apply cream to cold sore every 2 hours during waking periods for 4 days.

Contraindications/Warnings/ Precautions:

Penciclovir should only be used on herpes labialis on the lips and face.

Drug Interactions:

There are documented clinically significant drug interactions with penciclovir.

Pregnancy:

Category B: No evidence of risk in humans but studies inadequate.

Monitoring Requirements:

None

Brand names/Manufacturer:

DenavirŪ/Novartis Consumer Health Inc