Infants and children with impaired renal function require an appropriately modified dose, according to the degree of impairment (see Dosage in renal impairment).

Dosage in the elderly:

The possibility of renal impairment in the elderly must be considered and dosage should be adjusted accordingly (see Dosage in renal impairment below).

Adequate hydration should be maintained.

Dosage in renal impairment:

Caution is advised when administering Zovirax I.V. to patients with impaired renal function. Adequate hydration should be maintained.

Dosage adjustment for patients with renal impairment is based on creatinine clearance, in units of ml/min for adults and adolescents and in units of ml/min/1.73m2 for infants and children less than 13 years of age. The following adjustments in dosage are suggested:

Dosage adjustments in adults and adolescents:

Creatinine Clearance
 Dosage
 
25 to 50 ml/min
 The dose recommended above (5 or 10 mg/kg body weight) should be given every 12 hours.
 
10 to 25 ml/min
 The dose recommended above (5 or 10 mg/kg body weight) should be given every 24 hours.
 
0(anuric) to 10 ml/min
 In patients receiving continuous ambulatory peritoneal dialysis (CAPD) the dose recommended above (5 or 10 mg/kg body weight) should be halved and administered every 24 hours.
 
 In patients receiving haemodialysis the dose recommended above (5 or 10 mg/kg body weight) should be halved and administered every 24 hours and after dialysis.

Dosage adjustments in infants and children:

Creatinine Clearance
 Dosage
 
25 to 50 ml/min/1.73m2
 The dose recommended above (250 or 500 mg/m2 body surface area or 20 mg/kg body weight) should be given every 12 hours.
 
10 to 25 ml/min/1.73m2
 The dose recommended above (250 or 500 mg/m2 body surface area or 20 mg/kg body weight) should be given every 24 hours.
 
0(anuric) to 10 ml/min/1.73m2
 In patients receiving continuous ambulatory peritoneal dialysis (CAPD) the dose recommended above (250 or 500 mg/m2 body surface area or 20 mg/kg body weight) should be halved and administered every 24 hours.

In patients receiving haemodialysis the dose recommended above (250 or 500 mg/m2 body surface area or 20 mg/kg body weight) should be halved and administered every 24 hours and after dialysis

4.3 Contraindications
Hypersensitivity to aciclovir or valaciclovir, or to any of the excipients listed in section 6.1.
4.4 Special warnings and precautions for use
Adequate hydration should be maintained in patients given i.v. or high oral doses of aciclovir.

Intravenous doses should be given by infusion over one hour to avoid precipitation of aciclovir in the kidney; rapid or bolus injection should be avoided.

The risk of renal impairment is increased by use with other nephrotoxic drugs. Care is required if administering i.v. aciclovir with other nephrotoxic drugs.

Use in patients with renal impairment and in elderly patients:

Aciclovir is eliminated by renal clearance, therefore the dose must be adjusted in patients with renal impairment (see section 4.2 Posology and method of administration). Elderly patients are likely to have reduced renal function and therefore the need for dose adjustment must be considered in this group of patients. Both elderly patients and patients with renal i