Aciclovir: Dose adjustment for renal impairment

  • Dosing recommendations are based on creatinine clearance calculated using the Cockcroft-Gault equation.
  • Do not use eGFR estimates (available on PAS) for drug dosing purposes (for more information  click here )
  • To calculate creatinine clearance (CrCl) using the Cockcroft-Gault equation, use the creatinine clearance calculator :
  • Accurate estimation of CrCl is only possible in patients with STABLE renal function. In patients with rapidly changing renal function (i.e. ACUTE renal failure), the serum creatinine levels will no longer provide a true reflection of renal function.
  • Dose adjustment may not be appropriate in ACUTE renal impairment secondary to SEPSIS. In this case it is important to treat the infection aggressively for the first 24hrs and re-check renal function before reducing the dose accordingly.
  • (In 'acute on chronic' renal impairment the initial dose should correspond to the previous level of chronic renal impairment).

Intravenous

Crcl (ml/min) Dose
25 – 50

Normal dose every 12 hours

10 – 25

Normal dose every 24 hours

<10 50% of normal dose every 24 hours

 

Contact microbiology for advice on assays

Oral

Crcl (ml/min) Dose
25 – 50

Normal

10 – 25

Simplex: 200mg tds - qds; Zoster: 400 - 800mg tds

<10 Simplex 200mg bd; Zoster 400 - 800mg bd

 

Refer to Renal Pharmacist or Medicines Information for advice on dosing in haemodialysis and peritoneal dialysis.