Instructions for Use and Handling: Reconstitution: The required dose of Zovirax IV for infusion should be administered by slow IV infusion over a 1-hr period.
Zovirax IV for infusion should be reconstituted using the following volumes of either water for injections BP or sodium chloride IV injection BP (0.9% w/v) to provide a solution containing Zovirax 25 mg/ mL (Formulation: 250 mg vial; Volume of fluid for reconstitution: 10 mL).
From the calculated dose, determine the appropriate number and strength of vials to be used. To reconstitute each vial, add the recommended volume of infusion fluid and shake gently until the contents of the vial have dissolved completely.
Alternatively, the reconstituted solution may be further diluted to give an Zovirax concentration of not greater than 5 mg/mL (0.5% w/v) for administration by infusion. Add the required volume of reconstituted solution to the chosen infusion solution, as recommended as follows and shake well to ensure adequate mixing occurs.
For children, where it is advisable to keep the volume of infusion fluid to a minimum, it is recommended that dilution is on the basis of 4 mL reconstituted solution (Zovirax 100 mg) added to 20 mL of infusion fluid.
For adults, it is recommended that infusion bags containing 100 mL of infusion fluid are used, even when this would give an Zovirax concentration substantially, below 0.5% w/v.
Thus, one 100-mL infusion bag may be used for any dose between Zovirax 250 and 500 mg (10 and 20 mL of reconstituted solution) but a 2nd bag must be used for doses between 500 and 1000 mg.
When diluted in accordance with the recommended schedules, Zovirax IV for infusion is known to be compatible with the following infusion fluids and stable for up to 12 hrs at room temperature (15°-25°C): Sodium chloride IV infusion (0.45% and 0.9% w/v). Sodium chloride (0.18% w/v) and glucose (4% w/v) IV infusion. Sodium chloride (0.45% w/v) and glucose (2.5% w/v) IV infusion. Compound sodium lactate IV infusion (Hartmann's solution).
Zovirax IV for infusion when diluted in accordance with the above schedule will give an Zovirax concentration not greater than 0.5% w/v.
When reconstituted as directed, Zovirax IV for infusion has a pH of approximately 11.
Since no antimicrobial preservative is included, reconstitution and dilution must be carried out under full aseptic conditions, immediately before use and any unused solution discarded.
Reconstituted or diluted solutions should not be refrigerated.
Should any visible turbidity or crystallisation appear in the solution before or during infusion, the preparation should be discarded.