Famciclovir

Famciclovir 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).

Famciclovir

Clinical data
Pronunciation	/ˌfæmˈsaɪkloʊˌvɪər/[1]
Trade names	Famvir
AHFS/Drugs.com	Monograph
MedlinePlus	a694038
Pregnancy category	AU: B1
Routes of administration	By mouth
ATC code	J05AB09 (WHO) S01AD07 (WHO)
Legal status
Legal status	AU: S4 (Prescription only)[2] UK: POM (Prescription only) US: ℞-only
Pharmacokinetic data
Bioavailability	75–77%
Protein binding	20–25%
Metabolism	Liver, circulation, intestinal wall (to penciclovir)
Elimination half-life	2–2.3 hours
Excretion	Kidney, faecal
Identifiers
IUPAC name 2-[(acetyloxy)methyl]-4-(2-amino-9H-purin-9-yl)butyl acetate
CAS Number	104227-87-4 Y
PubChem CID	3324
DrugBank	DB00426 Y
ChemSpider	3207 Y
UNII	QIC03ANI02
KEGG	D00317 Y
ChEBI	CHEBI:4974 Y
ChEMBL	ChEMBL880 Y
CompTox Dashboard (EPA)	DTXSID0023038
ECHA InfoCard	100.158.713
Chemical and physical data
Formula	C14H19N5O4
Molar mass	321.337 g·mol−1
3D model (JSmol)	Interactive image
Melting point	103 °C (217 °F)
SMILES O=C(OCC(COC(=O)C)CCn1c2nc(ncc2nc1)N)C
InChI InChI=1S/C14H19N5O4/c1-9(20)22-6-11(7-23-10(2)21)3-4-19-8-17-12-5-16-14(15)18-13(12)19/h5,8,11H,3-4,6-7H2,1-2H3,(H2,15,16,18) Y Key:GGXKWVWZWMLJEH-UHFFFAOYSA-N Y
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Famciclovir was patented in 1983 and approved for medical use in 1994.^[3][4] In 2007, the United States Food and Drug Administration approved the first generic version of famciclovir. Generic tablets are manufactured by TEVA Pharmaceuticals and Mylan Pharmaceuticals.^[5][6]

Medical uses

Famciclovir is indicated for the treatment of herpes zoster (shingles),^[7] treatment of herpes simplex virus 2 (genital herpes),^[8] herpes labialis (cold sores) in immunocompetent patients^[9] 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.^{[citation needed]}

Adverse effects

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

Herpes

Early treatment

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.^[10][11][12] 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.^[13] Neither drug affected latency if treatment was delayed for several months.^[14]

History

Initially studied as compound BRL 42810, famciclovir grew out of the study of "several potential prodrugs of penciclovir", that were synthesized by M. R. Harnden and R. L. Jarvest from the Beecham Group plc. in the late 1980s. After showing promise on studies with mice, BRL 42810 (famciclovir) was selected for further evaluation and progression to studies in humans. ^[15]