Acyclovir is a guanosine analog, which works by inhibiting viral DNA polymerase. This slows down the rate at which viruses can replicate. Acyclovir is used primarily in the treatment of herpes simplex viruses 1 and 2, chickenpox, and shingles.

Foscarent can cause damage to the kidneys. To reduce the damaging effect, the patient may be put on intravenous fluids.