How to Dilute Voriconazole Injection
Voriconazole for injection must be reconstituted to 10 mg/mL with 19 mL of sterile water for injection, then further diluted to a final concentration between 0.5-5 mg/mL (not exceeding 5 mg/mL) in a compatible IV solution, and infused over 1-2 hours at a maximum rate of 3 mg/kg per hour. 1
Reconstitution Process
Step 1: Initial Reconstitution
- Add exactly 19 mL of sterile water for injection to the voriconazole powder vial
- Use a standard 20 mL non-automated syringe to ensure precise volume measurement
- The vial should create a vacuum that pulls the diluent in—discard the vial if no vacuum is present
- Shake the vial until all powder is completely dissolved
- This yields 20 mL of extractable volume at 10 mg/mL concentration 1
Step 2: Further Dilution
- Calculate the required volume of 10 mg/mL concentrate based on patient weight and prescribed dose (see dosing tables in drug label)
- Withdraw and discard an equal volume of diluent from your IV bag/bottle before adding the voriconazole concentrate
- Add the calculated volume of voriconazole concentrate to achieve a final concentration of 0.5-5 mg/mL (never less than 0.5 mg/mL or greater than 5 mg/mL)
- The diluted solution must be infused within specific timeframes 1
Compatible Diluents
Voriconazole can be diluted with 1:
- 0.9% Sodium Chloride
- 5% Dextrose
- Lactated Ringer's
- 5% Dextrose and Lactated Ringer's
- 5% Dextrose and 0.45% Sodium Chloride
- 5% Dextrose and 20 mEq Potassium Chloride
- 0.45% Sodium Chloride
- 5% Dextrose and 0.9% Sodium Chloride
Critical contraindication: Never use 4.2% Sodium Bicarbonate—the alkaline pH causes drug degradation 1
Administration Requirements
- Infuse over 1-2 hours only at a maximum rate of 3 mg/kg per hour
- Never administer as IV bolus injection
- Must use a separate IV line from blood products, concentrated electrolytes, or TPN 1
- Can run simultaneously with non-concentrated electrolyte solutions through separate lines 1
Storage and Stability
Once reconstituted:
- Use immediately from a microbiological standpoint
- If not used immediately, store at 2-8°C (36-46°F) for maximum 24 hours
- This is a single-use product—discard any unused solution
- Only use clear solutions without particles 1
Important stability data: Research shows that diluted voriconazole in PVC bags at 0.5 mg/mL stored at 4°C maintains >90% potency for 11 days in 0.9% sodium chloride and 9 days in 5% dextrose, though the FDA label recommends 24-hour maximum storage 2. At room temperature, stability drops significantly (below 90% within 2 days), so refrigeration is essential if not used immediately 2.
Critical Renal Considerations
In patients with creatinine clearance <50 mL/min: The IV formulation contains sulfobutyl-ether cyclodextrin (SBECD) vehicle that accumulates in renal impairment and may cause nephrotoxicity 3, 4, 3, 4, 5. Switch to oral voriconazole in these patients unless the benefit clearly outweighs the risk 4, 1. Monitor serum creatinine closely if IV administration is necessary 1.