Antiviral therapy of herpes simplex and varicella-zoster virus infections.

Antiviral treatment of herpesvirus infections is rapidly changing since the advent of new drugs with improved oral availability. The efficacy of valaciclovir, the prodrug of aciclovir, and famciclovir, the prodrug of penciclovir, in the treatment of herpes genitalis and acute herpes zoster has been well documented in large clinical trials. Both drugs are effective on zoster-associated pain. Brivudin and sorivudine which are the most active compounds against varicella-zoster virus (VZV) in cell culture have also been successful in the treatment of herpes zoster. Aciclovir is still the standard therapy of severe herpes simplex virus (HSV) and varicella virus infections. In patients treated with aciclovir, the mortality of herpes encephalitis has been reduced to about 25%. The development of resistance against aciclovir and the other nucleoside analogues has not been a problem to date in the treatment of immunocompetent individuals. However, in immunocompromised patients, aciclovir-resistant HSV strains often emerge. In such cases, intravenous foscarnet is the current treatment of choice.