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Trade namesDenavir, others
  • 2-amino-9-[4-hydroxy-3-(hydroxymethyl)butyl]-1H-purin-6(9H)-one
Clinical data
Drug classNucleoside analogue[2]
Main usesHerpes infection of the lip (cold sores)[2]
Side effectsIrritation at the site of application[2]
  • AU: B1
  • US: B (No risk in non-human studies)
Routes of
External links
Legal status
Bioavailability1.5% (oral), negligible (topical)
Protein binding<20%
MetabolismViral thymidine kinase
Elimination half-life2.2–2.3 hours
Chemical and physical data
Molar mass253.262 g·mol−1
3D model (JSmol)
Melting point275 to 277 °C (527 to 531 °F)
  • O=C2/N=C(\Nc1n(cnc12)CCC(CO)CO)N
  • InChI=1S/C10H15N5O3/c11-10-13-8-7(9(18)14-10)12-5-15(8)2-1-6(3-16)4-17/h5-6,16-17H,1-4H2,(H3,11,13,14,18) checkY

Penciclovir, sold under the brand name Denavir among others, is a medication used to treat herpes infection of the lip (cold sores).[2] It reduces the time to healing from 8 to 7 days.[3] It is applied to the area of infection.[2]

Common side effects include irritation at the site of application.[2] Use in pregnancy appears to be safe.[4] It is a nucleoside analogue and is similar to acyclovir.[2] Famciclovir is a precursor medication of penciclovir.[5]

Penciclovir was approved for medical use in the United States in 1996.[6][2] In the United States it costs about 800 USD for a 5 gram tube of cream as of 2021.[7] It is more expensive than other equally useful medications.[3]

Medical use

In herpes labialis, the duration of healing, pain and detectable virus is reduced by up to one day,[8] compared with the total duration of 2–3 weeks of disease presentation.


It is applied as a 1% cream every 2 hours when not sleep.[2] Treatment duration is four days.[2]

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) 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. 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.[citation needed]

Society and culture

It is the active ingredient in the cold sore medications Denavir (NDC 0135-0315-52), Vectavir and Fenivir.


  1. "Penciclovir". Merriam-Webster Dictionary. Retrieved 2016-01-22.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 "Penciclovir Monograph for Professionals". Archived from the original on 17 April 2021. Retrieved 27 October 2021.
  3. 3.0 3.1 "Penciclovir" (PDF). Archived (PDF) from the original on 15 April 2021. Retrieved 27 October 2021.
  4. "Penciclovir topical (Denavir) Use During Pregnancy". Archived from the original on 5 December 2020. Retrieved 27 October 2021.
  5. BNF 81: March-September 2021. BMJ Group and the Pharmaceutical Press. 2021. p. 672. ISBN 978-0857114105.
  6. Long SS, Pickering LK, Prober CG (2012). Principles and Practice of Pediatric Infectious Disease. Elsevier Health Sciences. p. 1502. ISBN 978-1437727029. Archived from the original on 2019-12-29. Retrieved 2021-03-22.
  7. "Penciclovir Prices, Coupons & Savings Tips - GoodRx". GoodRx. Archived from the original on 27 October 2021. Retrieved 27 October 2021.
  8. [ Archived 2012-02-19 at the Wayback Machine Farmaceutiska Specialiteter i Sverige - the Swedish official drug catalog. Archived 2011-01-21 at the Wayback Machine --> Vectavir. Retrieved on August 12, 2009. Translated from "Tiden för läkning, smärta och påvisbart virus förkortas med upp till ett dygn."

External links