C difficile risk
Oral Bioavailability


Serious Infections (e.g. CNS and Disseminated Zoster) 10 mg/kg IV q8h

Shingles 800mg PO 5 times per day

Prophylaxis dosing varies by indication

eGFR 0 - 10eGFR 10 - 25eGFR 25 - 50eGFR > 505 mg/kg IV q24h, or half of regular dose q24h10 mg/kg IV q24h10 mg/kg IV q12h10 mg/kg IV q8h (Regular dosing)

2.5-5 mg/kg IV q24h

Consider loading dose for serious infections

5-7.5 mg/kg IV q24h

Use upper end for CNS infections

General Information

Therapy for herpesviral infections (HSV and VZV) including encephalitis.

Prophylaxis of herpesviral infections if recurrent disease or immunocompromised.

Follow SCr as appropriate.

Check urine for crystals if AKI suspected.

  • GI upset

  • Phlebitis

  • Increased SCr

  • AKI from crystal nephropathy

Mycophenolate can increase the acyclovir concentration.

May diminish efficacy of zoster or varicella vaccine.

For oral indications, valacyclovir is the pro-drug, which is more bioavailable with more convenient dosing.

Antimicrobial class: Antiviral. Nucleoside analogue.

Pregnancy category: B

Average serum half life: 3 hours

Urine penetration: Therapeutic

CSF penetration: Therapeutic