Acyclovir, Zovirax IV

Reviewed by Brenda Hughes (Pharmacy), Dr Malcolm Battin
August 2015
Administration Newborn Drug Protocol Index Newborn Services Home Page


Dose and Administration

  1. 20 mg/kg/dose IV infusion by syringe pump over one hour.
Postmenstrual Age
Dosing Interval
≤29 q12h
30 to 36 q8h
36-41 q8h*
All gestations >28days
chronological age




Clinical Pharmacology

Antiviral agent which is highly active in vitro against herpes simplex (types 1 and 2) and varicella zoster viruses. Preferentially taken up by infected cells and then phosphorylated to the active compound aciclovir triphosphate. Acts as an inhibitor of, and substrate for, the herpes specified DNA polymerase. Prevents further viral DNA synthesis without affecting normal cellular processes. Toxicity to mammalian host cells is low.
Widely distributed throughout the body fluids and tissues. CSF concentrations approximately 50% that of plasma. Low binding (9-24%) to human plasma protein. Eliminated, mainly unchanged via the kidney, primarily by glomerular filtration. Elevated serum concentrations may be reduced by haemodialysis.

Possible Adverse Effects

Special Considerations

  1. Monitor

  1. Renal function. Check prior to commencing and during therapy. Use a slow infusion rate and maintaine adequate hydration to minimise the risk of renal dysfunction and renal crystalluria.
  1. Full Blood count.
  2. Electrolytes
  3. Liver function tests.
  4. Monitoring for 6 hourly dose interval:
  1. Resistant viral strains may emerge during long term therapy. There is NO evidence Aciclovir will stop transmission of the virus
  2. Aciclovir (Zovirax®) is licensed in New Zealand for the treatment of Herpes simplex infections in neonates