Zovirax IV

/ GSK

Route of administration: Slow intravenous infusion over 1 hour.
A course of treatment with Zovirax I.V. usually lasts 5 days, but this may be adjusted according to the patient’s condition and response to therapy. Treatment for herpes encephalitis usually lasts 10 days. Treatment for neonatal herpes infections usually lasts 14 days for mucocutaneous (skin-eye-mouth) infections and 21 days for disseminated or central nervous system disease.
The duration of prophylactic administration of Zovirax I.V. is determined by the
duration of the period at risk.
Dosage in adults: Patients with Herpes simplex (except herpes encephalitis) or Varicella zoster infections should be given Zovirax I.V. in doses of 5 mg/kg body weight every 8 hours provided renal function is not impaired (see Dosage in renal impairment).
Immunocompromised patients with Varicella zoster infections or patients with
herpes encephalitis should be given Zovirax I.V. in doses of 10 mg/kg body weight every 8 hours provided renal function is not impaired (see Dosage in renal impairment).
In obese patients dosed with intravenous aciclovir based on their actual body
weight, higher plasma concentrations may be obtained. Consideration should therefore be given to dosage reduction in obese patients and especially in those with renal impairment or the elderly.
Dosage in infants and children: The dose of Zovirax I.V. for infants and children aged between 3 months and 12 years is calculated on the basis of body surface area.
Infants and children 3 months of age or older with Herpes simplex (except herpes encephalitis) or Varicella zoster infections should be given Zovirax I.V. in doses of 250 mg per square metre of body surface area every 8 hours if renal function is not impaired.
In immunocompromised children with Varicella zoster infections or children with herpes encephalitis, Zovirax I.V. should be given in doses of 500 mg per square metre body surface area every 8 hours if renal function is not impaired.
The dosage of Zovirax I.V. in neonates and infants up to 3 months of age is
calculated on the basis of body weight.
The recommended regimen for infants treated for known or suspected neonatal
herpes is acyclovir 20 mg/kg body weight IV every 8 hours for 21 days for
disseminated and CNS disease, or for 14 days for disease limited to the skin and
mucous membranes. 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. Dosage adjustments in adults and adolescents: See prescribing information.

For the treatment of:
– Herpes simplex infections in immunocompromised patients and severe initial genital herpes in the nonimmunocompromised.
– Prophylaxis of Herpes simplex infections in immunocompromised patients.
– Varicella zoster infections.
– Herpes encephalitis.
– Herpes simplex infections in the neonate and infant up to 3 months of age.

Hypersensitivity to aciclovir or valaciclovir, or to any of the excipients.

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.
See prescribing information for full details.

Common: phlebitis, nausea, vomiting, reversible increases in liver-related enzymes, pruritus, urticaria, rashes (including photosensitivity), increases in blood urea and creatinine.
See prescribing information for full details.

Aciclovir is eliminated primarily unchanged in the urine via active renal tubular
secretion. Any drugs administered concurrently that compete with this mechanism may increase aciclovir plasma concentrations. Probenecid and cimetidine increase the AUC of aciclovir by this mechanism and reduce aciclovir renal clearance.
However no dosage adjustment is necessary because of the wide therapeutic index of aciclovir.
In patients receiving intravenous Zovirax caution is required during concurrent
administration with drugs which compete with aciclovir for elimination, because of the potential for increased plasma levels of one or both drugs or their metabolites.
Increases in plasma AUCs of aciclovir and of the inactive metabolite of
mycophenolate mofetil, an immunosuppressant agent used in transplant patients, have been shown when the drugs are coadministered.
If lithium is administered concurrently with high dose aciclovir IV, the lithium serum concentration should be closely monitored because of the risk of lithium toxicity.
Care is also required (with monitoring for changes in renal function) if administering intravenous Zovirax with drugs which affect other aspects of renal physiology (e.g. cyclosporin, tacrolimus).
An experimental study on five male subjects indicates that concomitant therapy with aciclovir increases AUC of totally administered theophylline with approximately 50%. It is recommended to measure plasma concentrations during concomitant therapy with aciclovir.

Pregnancy: Caution should be exercised by balancing the potential benefits of
treatment against any possible hazard.
Breast-feeding: Following oral administration of 200 mg five times a day, aciclovir has been detected in human breast milk at concentrations ranging from 0.6 to 4.1 times the corresponding plasma levels. These levels would potentially expose nursing infants to aciclovir dosages of up to 0.3 mg/kg body weight/day. Caution is therefore advised if Zovirax is to be administered to a nursing woman.

Overdosage of intravenenous aciclovir has resulted in elevations of serum
creatinine, blood urea nitrogen and subsequent renal failure. Neurological effects including confusion, hallucinations, agitation, seizures and coma have been described in association with overdosage.
Patients should be observed closely for signs of toxicity. Haemodialysis significantly enhances the removal of aciclovir from the blood and may, therefore, be considered an option in the management of overdose of this drug.