Antiviral therapy of herpes simplex

Herpes simplex virus (HSV) infections in immunocompromised patients are mor e severe and invasive than in non-immunocompromised patients. They are char acterised by prolonged viral shedding and a tendency to heal more slowly. I n addition, resistant viruses are exclusively isolated in immunocompromised patients, requiring other drugs with distinct mechanisms of action. The re ference compound for the treatment of HSV infections is acyclovir (ACV) tha t selectively inhibits HSV DNA replication with low host-cell toxicity. Rec ently, two molecules, valaciclovir (VACV), the L-valyl ester of ACV and fam ciclovir (FCV), the diacetyl ester of 6-deoxy-penciclovir (PCV), another po tent nucleoside analogue, were developed showing an increased oral bioavail ability compared to the original compounds. Foscavir (PFA) and more recentl y cidofovir (CDV) are drugs that do not need the viral thymidine kinase (TK ) to be activated and therefore are the appropriate candidates for the trea tment of resistant viruses emerging under acyclovir or penciclovir. (C) 200 0 Elsevier Science B.V. and International Society of Chemotherapy. All righ ts reserved.