C. diff Risk


Oral Bioavailability


Approximate Cost

Spectrum Of Activity


5-10mg/kg IV q8h

10mg/kg IV q8h for serious infections such as CNS and disseminated zoster

800mg PO 5 times per day for shingles

Prophylaxis dosing varies by indication

General Information

Common Usage

Therapy for herpes viral infections (HSV and VZV) including encephalitis

Prophylaxis of herpes viral infections if recurrent disease or immunocompromised

Drug Monitoring

Follow SCr as appropriate, check urine for crystals if suspect AKI

Adverse Effects

GI upset, phlebitis - common

Increased SCr

AKI from crystal nephropathy

Major Interactions

Mycophenolate can increase the acyclovir concentration

May diminish efficacy of zoster or varicella vaccine

Additional Information

For oral indications, consider Valacyclovir (pro-drug) which is more bioavailable with more convenient dosing.

IV normal saline recommended to prevent crystal nephropathy.


Antimicrobial class: Antiviral, nucleoside analogue

Pregnancy category: B

Average serum half life: 3.0

CSF penetration: Therapeutic

Urine penetration: Therapeutic