antibioticsbooks

Anti-Herpes Simplex
Virus and Varicella-
Zoster Virus Agents
32
Agents: acyclovir, valacyclovir, famciclovir
These agents are primarily used in the treatment
of infections caused by herpes simplex virus (HSV)
and varicella-zoster virus (VZV), though they are
active against some other viruses as well. Acyclovir
is poorly absorbed and must be given up to five
times daily when administered orally; valacyclovir
and famciclovir are pro-drugs that are absorbed
better and can be administered less frequently.
Only acyclovir can be administered intravenously,
and it is the agent of choice for serious HSV infections
such as encephalitis.
Mechanism of Action
These drugs are nucleoside analogs that, after
phosphorylation, are incorporated into the elongating
viral DNA strand just like cellular nucleotides;
but they lack the functional group that allows the
next nucleotide to be added, halting replication.
Spectrum
Good: HSV-1 and HSV-2
Moderate: VZV
Poor: Epstein-Barr virus (EBV), cytomegalovirus
(CMV), HIV