Zovirax Tablet Dosage/Direction for Use

Adults: Treatment of herpes simplex: For treatment of herpes simplex infections, 200 mg ZOVIRAX should be taken five times daily at approximately four-hourly intervals omitting the night time dose. Treatment should continue for five days but in severe initial infections may have to be extended.
In severely immune-compromised patients (e.g. after marrow transplant) or in patients with impaired absorption from the gut the dose can be doubled to 400 mg 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: For suppression of herpes simplex infections in immune-competent patients, 200 mg ZOVIRAX should be taken four times daily at approximately six-hourly intervals.
Many patients may be conveniently managed on a regimen of 400 mg ZOVIRAX taken twice daily at approximately twelve-hourly intervals.
Dosage titration down to 200 mg 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 infections on total daily doses of 800 mg 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: For prophylaxis of herpes simplex infections in immune-compromised patients, 200 mg ZOVIRAX should be taken four times daily at approximately six-hourly intervals.
In severely immune-compromised patients (e.g. after marrow transplant) or in patients with impaired absorption from the gut the dose can be doubled to 400 mg 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: For treatment of varicella and herpes zoster infections, 800 mg 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 immune-compromised 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 yields better results if initiated as soon as possible after onset of the rash.
Children: For treatment of herpes simplex infections, and for prophylaxis of herpes simplex infections in the immune-compromised, 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 varicella infections, children over the age of six years can be given 800 mg ZOVIRAX four times daily and children between the ages of two and six years can be given 400 mg ZOVIRAX four times daily.
Children below the age of two years can be given 200 mg ZOVIRAX four times daily. Dosing may be more accurately calculated as 20 mg ZOVIRAX/kg bodyweight (not to exceed 800 mg) four times daily. Treatment should continue for five days.
No specific data are available on the suppression of herpes simplex infections or the treatment of herpes zoster infections in immune-competent children.
Elderly: The possibility of renal impairment in the elderly must be considered and the dosage should be adjusted accordingly (see Renal Impairment as follows).
Adequate hydration of elderly patients taking high oral doses of ZOVIRAX should be maintained.
Renal Impairment: Caution is advised when administering ZOVIRAX oral formulations to patients with impaired renal function. Adequate hydration should be maintained.
In the treatment and prophylaxis of herpes simplex infections in patients with impaired renal function, the recommended oral doses will not lead to accumulation of aciclovir above levels that have been established safe by intravenous infusion. However, for patients with severe renal impairment (creatinine clearance less than 10 mL/minute) an adjustment of dosage to 200 mg 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 800 mg twice daily, at approximately twelve-hourly intervals, for patients with severe renal impairment (creatinine clearance less than 10 mL/minute) and to 800 mg three times daily, at intervals of approximately eight hours, for patients with moderate renal impairment (creatinine clearance in the range 10 to 25 mL/minute).