Herpes Medications

All currently available antiviral medications acyclovir, valaciclovir (Valtrex), and famciclovir (Famvir) do not cure herpes infections as they don't eradicate latent herpes virus. These drugs can’t eliminate the virus from the body, but work by stopping virus from multiplying. Antiviral medicines are prescribed to relieve the symptoms, reduce the duration of outbreak, hasten lesion healing, and to prevent passing the herpes virus to sexual partners.

Acyclovir (Zovirax)

Acyclovir, the first antiviral medication, was discovered by a team led by Gertrude B. Elion in the late 1970s. It is a very effective and safe medication with low rate of side effects.

The main disadvantages of acyclovir are low bioavailability and five-times-daily dosing regimen. It requires either higher dosing or intravenous administration for severe herpes infections, such as neonatal herpes, herpes encephalitis.

The advantage of acyclovir over other antiviral agents is lower cost.

Indications and uses:

• Treatment of initial and recurrent episodes of genital herpes
• Treatment of shingles
• Treatment of chickenpox
• Treatment of recurrent herpes labialis (cold sores)
• Prophylaxis of cytomegalovirus disease
• Treatment of neonatal herpes infections (parenteral)

Valacyclovir (Valtrex)

Valacyclovir (Valtrex) provides an excellent safe and effective alternative to its more old parent compound, acyclovir. It is just as effective as acyclovir in treating genital herpes and has the advantage that it need be taken only once or twice daily. Genital herpes transmission reduction is a recent indication for valacyclovir.

Valacyclovir has several important advantages. It is very well tolerated. The high bioavailability ensures more effective and consistent blood concentrations of the drug and enables less frequent dosage regimen compared to acyclovir. Valacyclovir appears to be more effective in decreasing pain associated with herpes zoster when compared to acyclovir2.

However, Valtrex is much more expensive than acyclovir, which has been available in generic form for a long time.

Indications and uses:

• Treatment of cold sores (herpes labialis)
• Treatment of initial and recurrent episodes of genital herpes
• Suppression of recurrent episodes of genital herpes
• Reduction of transmission of genital herpes
• Treatment of herpes zoster (shingles)
• Treatment of cold sores in children 12 years of age and older
• Treatment of chickenpox in children 2 to 18 years of age
• Prophylaxis of cytomegalovirus disease

Being a prodrug, valacyclovir does not have any antiviral activity until it is biotransformed into acyclovir.

Famciclovir (Famvir)

Famciclovir (Famvir) is a prodrug of penciclovir with improved oral bioavailability. Penciclovir is phosphorylated by viral enzyme thymidine kinase to its active form.

Famciclovir has the advantage of having convenient twice-daily dosing, long intracellular half-life1, and a better biovailability compared with acyclovir and valacyclovir.

The disadvantage of famciclovir is its high cost.

Indications and uses:

• Treatment of herpes zoster (shingles)
• Treatment of recurrent episodes of genital herpes
• Suppression of recurrent episodes of genital herpes
• Treatment of recurrent herpes labialis (cold sores)
• Management of initial episodes of genital herpes

Penciclovir (Denavir)

Denavir is available as 1% cream for topical use. There is no evidence that penciclovir (Denavir) offers an advantage over other drugs for the treatment of oral herpes.

Indications and uses:

• Treatment of recurrent herpes labialis (cold sores)

References

• 1. Earnshaw DL, Bacon TH, Darlison SJ, Edmonds K, Perkins RM, Vere Hodge RA Mode of antiviral action of penciclovir in MRC-5 cells infected with herpes simplex virus type 1 (HSV-1), HSV-2, and varicella-zoster virus. Antimicrob Agents Chemother 1992;36: 2747–2757
• 2. Lin WR, Lin HH, Lee SS, Tsai HC, Huang CK, Wann SR, Chen YS, Chiang SC, Yen MY, Liu YC. Comparative study of the efficacy and safety of valaciclovir versus acyclovir in the treatment of herpes zoster. J Microbiol Immunol Infect. 2001 Jun;34(2):138-42

Written for HealthyStock.net, October 2009.