Valacyclovir (Valtrex®) vs Famciclovir (Famvir®)

Based on "Antibiotic and Chemotherapy"
written by Roger G. Finch

Valacyclovir Famciclovir
Brand names
• Valtrex® • Famvir®
Drug class
• Antivirals
• Nucleoside analogues
Dose formulations
• Tablets • Tablets
Antiviral spectrum
• Herpes simplex virus 1
• Herpes simplex virus 2
• Varicella-zoster virus
• Cytomegalovirus
• Epstein-Barr virus
• Human herpesvirus type 6
• Human herpesvirus type 8
• Herpes simplex virus 1
• Herpes simplex virus 2
• Varicella-zoster virus
• Cytomegalovirus
• Hepatitis B virus 1
FDA-approved indications
• Herpes zoster (shingles) treatment
• Genital herpes: treatment of initial episodes and recurrent episodes, reduction of transmission
• Chronic suppressive therapy of recurrent genital herpes
• Chickenpox (varicella) treatment
• Cold sores treatment
• Herpes zoster (shingles) treatment
• Recurrent genital herpes treatment and suppression
• Cold sores treatment
"Off-label" uses
• Chronic fatigue syndrome 1 • Primary first episode of genital herpes 3
• Chronic hepatitis B 2
Mechanism of action
Nucleoside analogues inhibit viral DNA polymerase synthesis and as a result prevent viral replication.
  Upon ingestion, famciclovir undergoes rapid biotransformation to the active antiviral agent penciclovir.
Half-life
• 3 hours • 2.3 hours
• up to 10 hours in patients with renal impairment
Oral bioavailability
• 55% • 77%
• Famciclovir has superior bioavailability compared to valacyclovir.
Contraindications
• Hypersensitivity to valacyclovir, acyclovir • Hypersensitivity famciclovir or penciclovir (Denavir ®)
Side effects
• Headache
• Nausea
• Abdominal pain
• Headache
• Nausea
• Diarrhea
Pregnancy category
B
Cost
• Famciclovir is more expensive than valacyclovir.
• In the treatment of herpes zoster valacyclovir is rated as more cost-effective medication5.

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Valacyclovir vs. Famciclovir for Shingles

Both Valtrex® and Famvir® effectively accelerate resolution of zoster rash, lessen the severity of acute pain, and reduce duration of post-herpetic neuralgia.

Valacyclovir is comparable to famciclovir in speeding the resolution of acute shingles-associated pain and postherpetic neuralgia. Safety profiles for valacyclovir and famciclovir are similar, with headache and nausea the most common adverse events 5.

Recent Japanese study4 found that famciclovir provides significantly earlier reduction of acute pain in herpes zoster than valacyclovir.

Both medications have the same treatment regimens for shingles.

Valacyclovir (Valtrex®) dose:
1.000 mg 3 times daily for 7 days.

Famciclovir (Famvir®) dose:
500 mg 3 times daily for 7 days.

Valacyclovir vs. Famciclovir for Genital herpes

Both antiviral drugs Valtrex® and Famvir® are FDA-approved for genital herpes treatment and suppression.

Unlike Famvir®, Valtrex® is licensed for the treatment of newly acquired genital herpes infection. However, famciclovir is also recommended by CDC3 as effective therapy.

Valacyclovir appears to be somewhat better than famciclovir for suppression of genital herpes and associated shedding 6.

Further reading


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References

  • 1. Trépo C1, Jezek P, Atkinson G, Boon R, Young C. Famciclovir in chronic hepatitis B: results of a dose-finding study. J Hepatol. 2000 Jun;32(6):1011-8.
  • 2. Henderson TA. Valacyclovir treatment of chronic fatigue in adolescents. Adv Mind Body Med. 2014 Winter;28(1):4-14.
  • 3. 2015 Sexually Transmitted Diseases Treatment Guidelines. Genital HSV Infections. CDC
  • 4. Ono F, Yasumoto S, Furumura M, Hamada T, et al. Comparison between famciclovir and valacyclovir for acute pain in adult Japanese immunocompetent patients with herpes zoster. J Dermatol. 2012 Nov;39(11) PubMed
  • 5. Tyring SK, Beutner KR, Tucker BA, Anderson WC, Crooks RJ. Antiviral therapy for herpes zoster: randomized, controlled clinical trial of valacyclovir and famciclovir therapy in immunocompetent patients 50 years and older. Arch Fam Med. 2000 Sep-Oct;9(9):863-9. PubMed
  • 6. Wald A, Selke S, Warren T, Aoki FY, Sacks S, Diaz-Mitoma F, Corey L. Comparative efficacy of famciclovir and valacyclovir for suppression of recurrent genital herpes and viral shedding. Sex Transm Dis. 2006 Sep;33(9):529-33. PubMed

Published: February 03, 2018
Last updated: February 03, 2018

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