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Famciclovir structure.svg
Systematic (IUPAC) name
2-[(acetyloxy)methyl]-4-(2-amino-9H-purin-9-yl)butyl acetate
Clinical data
Trade names Famvir
AHFS/Drugs.com Monograph
MedlinePlus a694038
Routes of
Legal status
Legal status
  • S3 (Au), POM (UK), ℞-only (U.S.)
Pharmacokinetic data
Bioavailability 75–77%
Protein binding 20-25%
Metabolism Hepatic, circulation, intestinal wall (to penciclovir)
Biological half-life 2–2.3 hours
Excretion Renal, faecal
CAS Number 104227-87-4 YesY
ATC code J05AB09 (WHO) S01AD07 (WHO)
PubChem CID 3324
DrugBank DB00426 YesY
ChemSpider 3207 YesY
KEGG D00317 YesY
Chemical data
Formula C14H19N5O4
Molar mass 321.332 g/mol
Physical data
Melting point 103 °C (217 °F)

Famciclovir (INN; /ˌfæmˈsklˌvɪər/[1]) is a guanosine analogue antiviral drug used for the treatment of various herpesvirus infections, most commonly for herpes zoster (shingles). It is a prodrug form of penciclovir with improved oral bioavailability. Famciclovir is marketed under the trade name Famvir (Novartis).

On August 24, 2007, the United States Food and Drug Administration approved the first generic version of famciclovir.

Generic Famciclovir Tablets (125 mg, 250 mg, 500 mg) are manufactured by TEVA Pharmaceuticals and Mylan Pharmaceuticals.[2][3]


Famciclovir is indicated for the treatment of herpes zoster (shingles),[4] treatment of herpes simplex virus 2 (genital herpes),[5] herpes labialis (cold sores) in immunocompetent patients[6] and for the suppression of recurring episodes of herpes simplex virus 2. It is also indicated for treatment of recurrent episodes of herpes simplex in HIV patients.


Famciclovir comes as an oral tablet in 125 mg, 250 mg, and 500 mg dosage forms. To treat herpes zoster, Famciclovir is taken 500 mg every 8 hours (three times a day) for 7 days.[4] To treat genital herpes it is taken twice a day for 5 days.[5] To treat herpes labialis (cold sores), famciclovir is given as a single 1500 mg oral dose.[6] It is also sometimes given in one single large dose as opposed to several days of scheduled small doses. Among other side effects, Famciclovir may cause an upset stomach. Take famciclovir with food or milk.[7]

Adverse effects[edit]

Side effects: mild to extreme stomach upset, headaches, mild fever.


Early treatment[edit]

Several studies in humans and mice provide evidence that early treatment with famciclovir soon after the first infection with herpes can significantly lower the chance of future outbreaks. Use of famciclovir in this manner has been shown to reduce the amount of latent virus in the neural ganglia compared to no treatment or treatment with valaciclovir.[8][9][10] A review of human subjects treated for five days with famciclovir 250 mg three times daily during their first herpes episode found that only 4.2 percent experienced a recurrence within six months after the first outbreak, a fivefold decrease compared to the 19 percent recurrence in acyclovir-treated patients.[11] Neither drug affected latency if treatment was delayed for several months.[12] Despite these promising results, early famciclovir treatment for herpes in this or similar dosage regimes has yet to find mainstream adoption.[dubious ] As a result, some doctors and patients have opted for off-label use. One suggested regime is famciclovir at 10–20 mg/kg per day for 5–14 days, with treatment to commence as soon as possible after the first herpes infection (not the first symptoms or outbreak), and the most effective time for initiating treatment to be five days or less after the first herpes infection.[citation needed]


Famvir (famciclovir) vs Valtrex (valaciclovir) clinical trials done in 1997 found that long-term treatment with valaciclovir was more effective than famciclovir at suppressing latent viral shedding of Herpes, but the research was not released for 10 years by the funder, the owner of Famvir.[13][14][15]

See also[edit]


  1. ^ "Famciclovir". Merriam-Webster Dictionary. Retrieved 2016-01-22. 
  2. ^ "Recent Product Launches, Teva Pharmaceuticals USA". Retrieved 2008-02-21. [better source needed]
  3. ^ "Mylan Launches Generic Version of Famvir® Tablets" (Press release). Mylan. 20 April 2011. Archived from the original on July 23, 2011. Retrieved 21 April 2011. 
  4. ^ a b Tyring SK, Barbarash RA (1995). "Famciclovir for the Treatment of Acute Herpes Zoster: Effects on Acute Disease and Postherpetic Neuralgia". Annals of Internal Medicine. 123 (2): 89–96. doi:10.7326/0003-4819-123-2-199507150-00002. PMID 7778840. 
  5. ^ a b Luber AD, Flaherty JF (1996). "Famciclovir for Treatment of Herpesvirus Infections". Annals of Pharmacotherapy. 30 (9): 978–85. doi:10.1177/106002809603000913. PMID 8876860. 
  6. ^ a b Spruance SL, Bodsworth N (2006). "Single-Dose, Patient-Initiated Famciclovir: A Randomized, Double-Blind, Placebo-Controlled Trial for Episodic Treatment of Herpes Labialis". J. Am. Academ. Dermatol. 55 (1): 47–53. doi:10.1016/j.jaad.2006.02.031. PMID 16781291. 
  7. ^ "MedlinePlus Drug Information: Famciclovir". Archived from the original on 2007-06-10. Retrieved 2007-06-12. 
  8. ^ The effects of antiviral therapy on the distribution of herpes simplex virus type 1 to ganglionic neurons and its consequences during, immediately following and several months after treatment"[1]"
  9. ^ Famciclovir and Valaciclovir Differ in the Prevention of Herpes Simplex Virus Type 1 Latency in Mice: a Quantitative Study"[2]"
  10. ^ Persistence of Infectious Herpes Simplex Virus Type 2 in the Nervous System in Mice after Antiviral Chemotherapy"[3]"
  11. ^ Observation May Indicate A Possible Clinical Effect On Latency"[4]"
  12. ^ Thackray AM, Field HJ. (1996). "Differential effects of famciclovir and valaciclovir on the pathogenesis of herpes simplex virus in a murine infection model including reactivation from latency". J. Infect. Dis. 173 (2): 291–299. doi:10.1093/infdis/173.2.291. PMID 8568288. 
  13. ^ Comparative efficacy of famciclovir and valacyclovir for suppression of recurrent genital herpes and viral shedding. Sexually Transmitted Diseases (Vol 33, page 529). http://www.problemsinanes.com/pt/re/std/fulltext.00007435-200609000-00002.htm;jsessionid=Pc5JWB3P8ydgxrSbRTpk2p2h2R3Tkr2pFxSq2j361Q2RQ4Xm4DN0!760956446!181195628!8091!-1.
  14. ^ Another Case of Attempted Research Suppression: the Famvir vs Valtrex Study [5] (Archive)
  15. ^ PubMed 16778740

External links[edit]