Is there any treatment for herpes?
There are now several drugs available in Canada to treat herpes, such as acyclovir (Zovirax®), valacyclovir (Valtrex®), famciclovir (Famvir®), penciclovir (Denavir®), ganciclovir (Cytovene®, Vitrasert®), vidarabine (Vira-A®), cidofovir (Vistide®), and foscarnet (Foscavir®). These prescription drugs come in different formulations such as topical, oral and intravenous formulations. There is also a drug for cold sores that you can buy without a prescription called docanosol cream (Abreva®). Your physician will help in recommending an appropriate regimen for your specific circumstance.
Acyclovir and its related compounds, valacyclovir, famciclovir, and penciclovir, remain the first line drugs of choice for the treatment of herpes simplex infections. Acyclovir is available in an oral, an intravenous, and a topical formulation. Valacyclovir and famciclovir are only available in oral form and not approved in Canada for use in children. Unfortunately only 10-20% of acyclovir is absorbed when taken orally. In contrast, valacyclovir is 80% absorbed and then converted to acyclovir in the liver.
Acyclovir is a “nucleoside analogue” (it can insert itself into virus DNA during virus replication) and specifically targets virus infected cells. It prevents the production of new virus by stopping viral DNA from properly forming. Famciclovir and valacyclovir work in a similar manner to acyclovir. Because of the way they act, these 3 drugs require the virus to reactivate in order to be effective. Therefore, they are only effective against virus that has escaped from the nerve-cell and is replicating in other parts of the body. Thus, they do not cure a ‘dormant’ (latent) HSV infection, since the latent virus is not replicating. There is no antiviral treatment available that can eradicate latent HSV infection.
Vidarabine, one of the first HSV antiviral drugs available, is less safe than acyclovir and is only used in a 3% ointment form in North America, as treatment against herpes infections of the eye.
Foscarnet, another of the early anti-herpes drugs, was only used in life threatening HSV infection due to toxicity. It is now used in serious HSV infection if acyclovir does not work.