Famciclovir

Famciclovir
Names
Pronunciation/ˌfæmˈsaɪkloʊˌvɪər/[1]
Trade namesFamvir, others
IUPAC name
  • 2-[(acetyloxy)methyl]-4-(2-amino-9H-purin-9-yl)butyl acetate
Clinical data
Drug classAntiviral
Main usesHerpes zoster (shingles), herpes simplex[2]
Side effectsHeadache, nausea, diarrhea[3]
Pregnancy
category
  • AU: B1
  • US: B (No risk in non-human studies)
    Routes of
    use    		By mouth
    External links
    AHFS/Drugs.comMonograph
    US NLMFamciclovir
    MedlinePlusa694038
    Legal
    Legal status
    • AU: S3 (Pharmacist only)
    • UK: POM (Prescription only)
    • US: ℞-only
    Pharmacokinetics
    Bioavailability75–77%
    Protein binding20–25%
    MetabolismLiver, circulation, intestinal wall (to penciclovir)
    Elimination half-life2–2.3 hours
    ExcretionKidney, faecal
    Chemical and physical data
    FormulaC14H19N5O4
    Molar mass321.337 g·mol−1
    3D model (JSmol)
    Melting point103 °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) checkY
    • Key:GGXKWVWZWMLJEH-UHFFFAOYSA-N checkY

    Famciclovir, sold under the brand name Famvir among others, is an antiviral used to treat herpes zoster (shingles) and herpes simplex.[2] It is used for genital herpes as well as cold sores and may be used to treat active outbreaks and to prevent outbreaks.[3] It is taken by mouth.[3]

    Common side effects include headache, nausea, and diarrhea.[3] Lower doses may be used in people with kidney problems.[3] While there is no evidence of harm in pregnancy, such use has not been well studied.[4] It is a prodrug of penciclovir.[2] This results in a guanosine analogue which blocks viral DNA polymerase.[2]

    Famciclovir was patented in 1983 and approved for medical use in 1994.[5][6] It is available as a generic medication.[7] In the United Kingdom 14 tablets of 500 mg costs the NHS about £280 as of 2021.[7] This amount in the United States is about 16 USD.[8]

    Medical uses

    Famciclovir is indicated for the treatment of herpes zoster (shingles),[9] treatment of herpes simplex virus 2 (genital herpes),[10] herpes labialis (cold sores) in immunocompetent people[11] 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.

    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.[12][13][14] 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.[15] Neither drug affected latency if treatment was delayed for several months.[16]

    Dosage

    For herpes zoster it is used at a dose of 500 mg three times per day for 7 days.[2]

    Treatment of a first episode of genital herpes is with 250 mg three times per day for 5 days.[7] This may be used twice per day to prevent outbreaks.[7]

    Side effects

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

    Society and culture

    Generic tablets are manufactured by TEVA Pharmaceuticals and Mylan Pharmaceuticals.[17][18]

    See also

    References

    1. ↑ "Famciclovir". Merriam-Webster Dictionary. Retrieved 2016-01-22.
    2. 1 2 3 4 5 "Famciclovir". LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. National Institute of Diabetes and Digestive and Kidney Diseases. 2012. Archived from the original on 15 May 2021. Retrieved 10 December 2021.
    3. 1 2 3 4 5 "Famciclovir Monograph for Professionals". Drugs.com. Archived from the original on 16 November 2021. Retrieved 10 December 2021.
    4. ↑ "Famciclovir (Famvir) Use During Pregnancy". Drugs.com. Archived from the original on 29 November 2020. Retrieved 10 December 2021.
    5. ↑ 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 2020-12-06.
    6. ↑ Fischer J, Ganellin CR (2006). Analogue-based Drug Discovery. John Wiley & Sons. p. 504. ISBN 9783527607495. Archived from the original on 2016-12-20. Retrieved 2020-12-06.
    7. 1 2 3 4 BNF 81: March-September 2021. BMJ Group and the Pharmaceutical Press. 2021. p. 675. ISBN 978-0857114105.
    8. ↑ "Famciclovir Prices, Coupons & Savings Tips - GoodRx". GoodRx. Retrieved 10 December 2021.
    9. ↑ Tyring S, Barbarash RA, Nahlik JE, Cunningham A, Marley J, Heng M, et al. (July 1995). "Famciclovir for the treatment of acute herpes zoster: effects on acute disease and postherpetic neuralgia. A randomized, double-blind, placebo-controlled trial. Collaborative Famciclovir Herpes Zoster Study Group". Annals of Internal Medicine. 123 (2): 89–96. doi:10.7326/0003-4819-123-2-199507150-00002. PMID 7778840. S2CID 35498460.
    10. ↑ Luber AD, Flaherty JF (September 1996). "Famciclovir for treatment of herpesvirus infections". The Annals of Pharmacotherapy. 30 (9): 978–85. doi:10.1177/106002809603000913. PMID 8876860. S2CID 27057728.
    11. ↑ Spruance SL, Bodsworth N, Resnick H, Conant M, Oeuvray C, Gao J, Hamed K (July 2006). "Single-dose, patient-initiated famciclovir: a randomized, double-blind, placebo-controlled trial for episodic treatment of herpes labialis". Journal of the American Academy of Dermatology. 55 (1): 47–53. doi:10.1016/j.jaad.2006.02.031. PMID 16781291.
    12. ↑ Thackray AM, Field HJ (October 2000). "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". The Journal of General Virology. 81 (Pt 10): 2385–2396. doi:10.1099/0022-1317-81-10-2385. PMID 10993926.
    13. ↑ Thackray AM, Field HJ (July 1998). "Famciclovir and valaciclovir differ in the prevention of herpes simplex virus type 1 latency in mice: a quantitative study". Antimicrobial Agents and Chemotherapy. 42 (7): 1555–62. doi:10.1128/AAC.42.7.1555. PMC 105644. PMID 9660982.
    14. ↑ Thackray AM, Field HJ (January 2000). "Persistence of infectious herpes simplex virus type 2 in the nervous system in mice after antiviral chemotherapy". Antimicrobial Agents and Chemotherapy. 44 (1): 97–102. doi:10.1128/aac.44.1.97-102.2000. PMC 89634. PMID 10602729.
    15. ↑ "Observation May Indicate A Possible Clinical Effect On Latency". Doctor's Guide Publishing Limited. Archived from the original on 2012-02-16.
    16. ↑ Thackray AM, Field HJ (February 1996). "Differential effects of famciclovir and valaciclovir on the pathogenesis of herpes simplex virus in a murine infection model including reactivation from latency". The Journal of Infectious Diseases. 173 (2): 291–9. doi:10.1093/infdis/173.2.291. PMID 8568288.
    17. ↑ "Recent Product Launches, Teva Pharmaceuticals USA". Archived from the original on 2011-11-08. Retrieved 2008-02-21.
    18. ↑ "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.
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