Antiviral Agents in the Hematopoietic Stem Cell Transplant Population: Acyclovir, Valacyclovir, Penciclovir, and Famciclovir

Over the last five decades, the nucleoside analogues acyclovir and penciclovir, and their respective prodrugs, valacyclovir and famciclovir, have been used to prevent and control viral infections commonly found in the hematopoietic cell transplantation community. Despite all being guanosine analogs, structural differences yield variability in their affinity to viral enzymes and subsequent viral control. What follows is an introduction to each agent, highlighting their indications for use and dosing, pharmacokinetic and pharmacodynamic properties, and clinical data supporting their utilization as both preventative and treatment modalities.