Posology : מינונים

4.2    Posology and method of administration
Dosage in Adults

Treatment of herpes simplex infections: 200mg Zovirax should be taken five times daily at approximately four hourly intervals omitting the night time dose. Treatment should continue for 5 days, but in severe initial infections this may have to be extended.

In severely immunocompromised patients (e.g. after marrow transplant) or in patients with impaired absorption from the gut the dose can be doubled to 400mg Zovirax or alternatively intravenous dosing could be considered.


Dosing should begin as early as possible after the start of an infection; for recurrent episodes this should preferably be during the prodromal period or when lesions first appear.


Suppression of herpes simplex infections in immunocompetent patients: 200mg Zovirax should be taken four times daily at approximately six-hourly intervals.


Many patients may be conveniently managed on a regimen of 400mg Zovirax twice daily at approximately twelve-hourly intervals.


Dosage titration down to 200mg Zovirax taken thrice daily at approximately eight- hourly intervals or even twice daily at approximately twelve-hourly intervals, may prove effective.


Some patients may experience break-through infection on total daily doses of 800mg Zovirax.


Therapy should be interrupted periodically at intervals of six to twelve months, in order to observe possible changes in the natural history of the disease.


Prophylaxis of herpes simplex infections in immunocompromised patients: 200mg Zovirax should be taken four times daily at approximately six hourly intervals.


In severely immunocompromised patients (e.g. after marrow transplant) or in patients with impaired absorption from the gut, the dose can be doubled to 400mg Zovirax or, alternatively, intravenous dosing could be considered.


The duration of prophylactic administration is determined by the duration of the period at risk.


Treatment of varicella and herpes zoster infections: 800mg Zovirax should be taken five times daily at approximately four-hourly intervals, omitting the night time dose.
Treatment should continue for seven days.


In severely immunocompromised patients (e.g. after marrow transplant) or in patients with impaired absorption from the gut, consideration should be given to intravenous dosing.


Dosing should begin as early as possible after the start of an infection: treatment of herpes zoster yields better results if initiated as soon as possible after the onset of the rash. Treatment of chickenpox in immunocompetent patients should begin within 24 hours after onset of the rash.


Dosage in Children

Treatment of herpes simplex infections, and prophylaxis of herpes simplex infections in the immunocompromised: Children aged two years and over should be given adult dosages and children below the age of two years should be given half the adult dose.
For treatment of neonatal herpes virus infections, intravenous aciclovir is recommended.


Treatment of varicella infections:
6 years and over: 800mg Zovirax four times daily.
2 to 5 years: 400mg Zovirax four times daily.
Under 2 years: 200mg Zovirax four times daily.
Treatment should continue for five days.
Dosing may be more accurately calculated as 20mg/kg body weight (not to exceed 800mg) Zovirax four times daily.


No specific data are available on the suppression of herpes simplex infections or the treatment of herpes zoster infections in immunocompetent children.


Dosage in the Elderly

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


Adequate hydration of elderly patients taking high oral doses of aciclovir should be maintained.



Dosage in Renal Impairment

Caution is advised when administering aciclovir to patients with impaired renal function. Adequate hydration should be maintained.
In the management of herpes simplex infections in patients with severe renal impairment (creatinine clearance less than 10 ml/minute) an adjustment of dosage to 200 mg aciclovir twice daily at approximately twelve-hourly intervals is recommended.
In the treatment of varicella and herpes zoster infections it is recommended to adjust the dosage to 800mg aciclovir twice daily at approximately twelve-hourly intervals for patients with severe renal impairment (creatinine clearance less than 10ml/minute), and to 800mg aciclovir three times daily at intervals of approximately eight hours for patients with moderate renal impairment (creatinine clearance in the range 10 to 25ml/minute).