C difficile risk
Oral Bioavailability


eGFR 0 - 10eGFR 10 - 25eGFR 25 - 50eGFR > 505mg/kg IV q24h, or half of regular dose q24h10mg/kg IV q24h10mg/kg IV q12h10mg/kg IV q8h

2.5-5mg/kg IV q24h

Consider loading dose for serious infections

5-10 mg/kg IV q24h.

Use upper end for CNS infections

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

Herpes zoster
800mg PO five times per day

Prophylaxis dosing varies by indication

Given a current drug shortage, intravenous prescriptions for acyclovir beyond 24 hours will need approval by Infectious Disease

General Information

Acyclovir is used to treat herpes virus infections (e.g. HSV and VZV) but not CMV infections.

Acyclovir is also used for prophylaxis in transplantation protocols for patients who are immunocompromised.

Monitor serum creatinine and monitor for neurotoxicity.

  •  Gastrointestinal intolerance

  •  Phlebitis with IV formulation

  •  Increased serum creatinine and hematuria secondary to crystal nephropathy

Mycophenolate can increase serum concentrations of acyclovir.

For indications when oral acyclovir can be used, 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

CSF penetration: Therapeutic

Urine penetration: Therapeutic