Instructions for Use/Handling: ZOVIRAX Dispersible Tablets may be swallowed whole or with a little water, or dispersed in a minimum of 50 ml of water.
Dilution: ZOVIRAX oral suspension 200mg/5mL, may be diluted with an equal volume of either Syrup or Sorbitol Solution 70 per cent (Non-crystallising).
The diluted product is stable for 4 weeks at 25°C but it is recommended that all dilutions are freshly prepared.
When a dilution of ZOVIRAX oral suspension, 400mg/5mL is prescribed, it is recommended that the 200mg/5mL suspension is dispensed.
Reconstitution: The required dose of ZOVIRAX IV for infusion should be administered by slow IV infusion over a one-hour period.
ZOVIRAX IV for infusion should be reconstituted using the following volumes of either Water for Injections or Sodium Chloride Injection (0.9% w/v) to provide a solution containing 25 mg ZOVIRAX per mL: (See Table 3.)
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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.
After reconstitution ZOVIRAX IV for infusion may be administered by a controlled-rate infusion pump.
Alternatively, the reconstituted solution may be further diluted to give a 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 and neonates, 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 (100 mg ZOVIRAX) 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 a ZOVIRAX concentration substantially below 0.5% w/v. Thus one 100 mL infusion bag may be used for any dose between 250 mg and 500 mg ZOVIRAX (10 and 20 mL of reconstituted solution) but a second 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 hours at room temperature (25°C): Sodium Chloride Intravenous Infusion (0.45% and 0.9% w/v);
Sodium Chloride (0.18% w/v) and Glucose (4% w/v) Intravenous Infusion;
Sodium Chloride (0.45% w/v) and Glucose (2.5% w/v) Intravenous Infusion;
Compound Sodium Lactate Intravenous Infusion (Hartmann's Solution).
ZOVIRAX IV for infusion when diluted in accordance with the above schedule will give a 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.
Incompatibilities: None known.