Penciclovir

 ( Anti-herpes Virus Drugs ) 

Penciclovir is a guanosine analogue antiviral medication used for the treatment of various herpesvirus infections. It is a nucleoside analogue which exhibits low toxicity and good selectivity. It is used as a topical treatment. It is sold under the brand name Denavir among others.

Penciclovir was approved for medical use in 1996.

---

Medical use In herpes labialis, the duration of healing, pain and detectable virus is reduced by up to one day, Farmaceutiska Specialiteter i Sverige - the Swedish official drug catalog. [http://www.fass.se Fass.se --> Vectavir. Retrieved on August 12, 2009. Translated from "Tiden för läkning, smärta och påvisbart virus förkortas med upp till ett dygn." compared with the total duration of 2–3 weeks of disease presentation.

---

Mechanism of action 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) 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. First, 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. Second, 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 are 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 higher given equivalent cellular doses.

Post Comment