Famvir  

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	7577%
Protein binding	20-25%
Metabolism	Hepatic, circulation, intestinal wall (to penciclovir)
Half life	22.3 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 /fæmsaklvr/) 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 (Schering-Plough).

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]

Indications

Famciclovir is indicated for the treatment of herpes zoster (shingles). ^[2] Treatment of herpes simplex virus 2 (genital herpes) ^[3] and herpres 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 125mg, 250mg, and 500mg dosage forms. To treat herpes zoster, Famciclovir is taken 500mg 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 1500mg 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 five-fold 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 1020 mg/kg per day for 514 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

External links

• Famvir product website run by Schering-Plough

See also

• Penciclovir

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Famvir what is famvir prescribed for? Thursday, 12/1/2005 3:06:58 PM  1 Reply