Denavir (Penciclovir)

Denavir Review

Denavir is a topical antiviral medication used for recurrent cold sores (herpes labialis) on the lips and face in otherwise healthy adult patients. Denavir topical may also be used for purposes other than those listed in this medication guide.

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Denavir Drug Class and Mechanism

Penciclovir is inactive in its initial form. Within a virally infected cell a viral thymidine kinase adds a phosphate group to the penciclovir molecule; this is the rate-limiting step in the activation of penciclovir. Cellular (human) kinases then add two more phosphate groups, producing the active penciclovir triphosphate. This activated form inhibits viral DNA polymerase, thus impairing the ability of the virus to replicate within the cell. The selectivity of penciclovir may be attributed to two factors. Firstly, cellular thymidine kinases phosphorylate the parent form significantly less rapidly than does the viral thymidine kinase, so the active triphosphate is present at much higher concentrations in virally infected cells than in uninfected cells. Secondly, the activated drug binds to viral DNA polymerase with a much higher affinity than to human DNA polymerases. As a result penciclovir exhibits negligible cytotoxicity to healthy cells. The structure and mode of action of penciclovir is very similar to that of other nucleoside analogues such as the more widely used aciclovir. A difference between aciclovir and penciclovir is that the active triphosphate form of penciclovir persists within the cell for a much longer time than the activated form of aciclovir, so the concentration within the cell of penciclovir will be relatively higher given equivalent cellular doses.

Denavir Uses

Penciclovir (INN) (pronounced) 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. Because penciclovir is absorbed poorly when given orally (by mouth) it is used more as a topical treatment, and is the active ingredient in the cold sore medications Denavir and Fenistil. Famciclovir is a prodrug of penciclovir with improved oral bioavailability.Denavir comes as a cream. It is usually used externally every 2 hours while you are awake for 4 days. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist or doctor to explain any part you do not understand. Use Denavir exactly as directed. Do not use more or less of it or use it more often than prescribed by your doctor. Use Denavir as soon as possible after symptoms appear.

Denavir Side Effects

Although side effects from penciclovir are not common, they can occur. Tell your doctor if any of these symptoms are severe or do not go away:

headache
irritation at the site of application

Denavir Pregnancy

No adverse effects on the course and outcome of pregnancy or on fetal development were noted in rats and rabbits following the intravenous administration of penciclovir at doses of 80 and 60 mg/kg/day, respectively (estimated human equivalent doses of 13 and 18 mg/kg/day for the rat and rabbit, respectively based on body surface area conversion; the body surface area doses being 260 and 355x the maximum recommended dose following topical application of the penciclovir cream). There are, however no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, penciclovir should be used during pregnancy only if clearly needed.

Denavir Overdose

Since penciclovir is poorly absorbed following oral administration adverse reactions related to penciclovir ingestion are unlikely. There is no information on overdose.

Denavir More Information

Do not use other topical medications to treat the same area at them same time as Denavir topical, unless otherwise directed by your doctor. No other medicines have been reported to interact with Denavir topical. Talk to your doctor or pharmacist before taking other prescription or over-the-counter medications during treatment with Denavir topical.