Antivirals for Herpes

Herpes antiviral drugs are used to treat herpes - an infection caused by herpes simplex virus 1 or 2. It mainly affects the mouth or genital area.

Herpes simplex virus type 1 (HSV-1) usually affects lips, mouth, and face (herpes labialis). It is the most common type of herpes simplex virus and is usually acquired in childhood. HSV-1 can also cause genital herpes through transmission during oral-genital sex.

Herpes simplex virus 2 (HSV-2) is sexually transmitted and is usually associated with genital ulcers or sores. HSV-1 genital herpes usually causes fewer recurrences than HSV-2.

The following designations are given for genital HSV infections:

• Primary
• Nonprimary first-episode
• Recurrent
• Asymptomatic viral shedding

Herpes symptoms:

• mouth sores
• genital lesions (male)
• genital lesions (female)
• blisters and/or ulcers - most frequent on the mouth, lips and gums or genitalia
• fever blisters
• fever - may be present especially during the first episode
• enlargement of lymph nodes in the neck or groin

The hallmark of the herpes viruses is their ability to establish permanent latent residence within the neuronal ganglia and to reactivate during times of stress, trauma, and other predisposing factors. Humans are the only natural host and reservoir for the HSV viruses.

Antiviral Drugs

Antivirals, guanosine nucleoside analogs, are used to treat herpes simplex virus infections. Nucleoside analogues disrupt viral DNA replication of HSV. Antiviral drugs can help prevent or minimize recurrences of herpes, speed recovery of an outbreak, reduce pain and decrease the chances of spreading the virus. However, they do not cure herpes infection.

When initiated within 72 hours, oral antiviral therapy is beneficial in reducing the duration and intensity of outbreak and providing more rapid skin lesion healing.

The following prescription medicines are approved by the US FDA for herpes treatment:

• Acyclovir (Zovirax), the first and the oldest antiviral drug, has been used for many years and is widely available in generic form. Acyclovir tablets are used to treat genital herpes, and cream formulation is used for cold sores. Topical creams are not recommended for genital herpes.
• Valacyclovir (Valtrex) can be used as an alternative to acyclovir to treat herpes infections and shingles. It requires less frequent dosing and usually has similar or better results than acyclovir. However, it is quite expensive.
• Penciclovir (Denavir) is used in mild recurrent herpes labialis.
• Famciclovir (Famvir) is a prodrug of penciclovir, a purine analog. Famciclovir has high bioavailability of 77%. When taken, the body converts famciclovir to the long acting penciclovir.

Episodic therapy
Episodic therapy means taking the drug only during an outbreak to speed healing. Antiviral drugs are most effective if they are taken when you first notice the prodromal symptoms (tingling and pain), just before blisters or sores appear, of a herpes outbreak and if they are taken for the next 5 to 7 days or until symptoms go away.

For first episodes, the healing time can be dramatically reduced. For recurrences, the outbreak can be shortened by about two days.

Suppressive, or continuous, therapy
In persons with more than 6 recurrences of genital herpes per year, chronic antiviral therapy may be prescribed to reduce recurrences.

Suppressive therapy means taking an antiviral medication daily as a preventative - to keep HSV in control, reduce flare ups and lessen symptoms. Suppressive therapy can lower the number of outbreaks and, for some, prevent them altogether. This therapy also reduces asymptomatic shedding, and research studies are determining whether on-going antiviral medication can help prevent transmission.

All antivirals are similarly effective against HSV-1 and HSV-2 strains and are only available by prescription.

Genital Warts

Genital warts are soft wart-like growths on the genitals caused by a viral skin disease. Genital warts are a type of sexually transmitted disease (STD). The virus responsible for genital warts is called human papilloma virus (HPV).

All medicines used to treat HPV disease are applied topically on cutaneous surfaces. Two categories of prescription medications are effective in treating genital warts. The first category, the immune response modifiers (i.e., imiquimod (Aldara), interferon alfa), is primarily used in treatment of external anogenital warts or condylomata acuminata. The second category consists of the cytotoxic agents, which include drugs such as podofilox (Condylox), podophyllin.

Last Updated: January 2012