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Famciclovir
Systematic (IUPAC) name
2-[(acetyloxy)methyl]-4-(2-amino-9H-purin-9-yl)butyl acetate
Identifiers
CAS number 104227-87-4
ATC code J05AB09 S01AD07
PubChem 3324
DrugBank APRD00600
Chemical data
Formula C14H19N5O4 
Mol. mass 321.332 g/mol
Physical data
Melt. point 103 °C (217 °F)
Pharmacokinetic data
Bioavailability 75–77%
Protein binding 20-25%
Metabolism Hepatic, circulation, intestinal wall (to penciclovir)
Half life 2–2.3 hours
Excretion Renal, faecal
Therapeutic considerations
Pregnancy cat. B1 (Au), B (U.S.)
Legal status S4 (Au), POM (UK), ℞-only (U.S.)
Routes Oral
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Famciclovir (INN) (pronounced /fæmˈsaɪklɵvɪr/) is a guanine 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 Kfar-Sava, Israel-based TEVA Pharmaceuticals.[1]

Contents

Indications

Famciclovir is indicated for the treatment of herpes zoster (shingles).[2] Treatment of herpes simplex virus 2 (genital herpes) [3] and herpes labialis (cold sores) in immunodeficient patients.[4] Suppression of recurring episodes of herpes simplex virus 2. Treatment of recurrent episodes of herpes simplex in HIV patients.

Dosing

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.[2] To treat genital herpes it is taken twice a day for 1 day.[3] To treat herpes labialis (cold sores), famciclovir is given as a single 1500 mg oral dose.[4] 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.[5]

Adverse effects

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

Herpes post-exposure prophylaxis use

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 of herpes. Use of Famciclovir in this manner, known as post-exposure prophylaxis, has been shown to reduce the amount of latent virus in the neural ganglia.[6][7][8] 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.[9] Despite these promising results, early Famciclovir treatment for herpes in this or similar dosage regimes has yet to find mainstream adoption. 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.[10]

References

  1. ^ "Recent Product Launches, Teva Pharmaceuticals USA". http://www.tevausa.com/default.aspx?pageid=75. Retrieved 2008-02-21. 
  2. ^ a b Tyring SK, Barbarash RA (1995). "Famciclovir for the Treatment of Acute Herpes Zoster: Effects on Acute Disease and Postherpetic Neuralgia". Ann. Intern. Med. 123 (2): 89–96. PMID 778840. 
  3. ^ a b Luber AD, Flaherty JF (1996). "Famciclovir for Treatment of Herpesvirus Infections". Ann. Pharmacother. 30 (9): 978–85. PMID 8876860. 
  4. ^ a b Spraunce 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. PMID 16781291. 
  5. ^ "MedlinePlus Drug Information: Famciclovir". http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a694038.html. Retrieved 2007-06-12. 
  6. ^ 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]"
  7. ^ Famciclovir and Valaciclovir Differ in the Prevention of Herpes Simplex Virus Type 1 Latency in Mice: a Quantitative Study"[2]"
  8. ^ Persistence of Infectious Herpes Simplex Virus Type 2 in the Nervous System in Mice after Antiviral Chemotherapy"[3]"
  9. ^ Observation May Indicate A Possible Clinical Effect On Latency"[4]"
  10. ^ 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. PMID 8568288. 

External links

See also

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