Diluting 50% Dextrose in Water (D50W) to 25% Dextrose in Water (D25W)
To convert 50 mL of 50% dextrose solution to 25% concentration, add 50 mL of sterile water to the original 50 mL, yielding a total volume of 100 mL at 25% concentration.
Dilution Calculation
The dilution follows the basic principle: C₁V₁ = C₂V₂, where:
- C₁ = initial concentration (50%)
- V₁ = initial volume (50 mL)
- C₂ = desired concentration (25%)
- V₂ = final volume (unknown)
Solving for final volume:
- (50%)(50 mL) = (25%)(V₂)
- V₂ = 100 mL total final volume
Therefore, add 50 mL of sterile water to achieve the target concentration 1.
Practical Application
- Start with your 50 mL of D50W
- Add an equal volume (50 mL) of sterile water or 0.9% sodium chloride for injection
- Mix thoroughly to ensure homogeneous distribution
- The resulting 100 mL solution will be 25% dextrose 1
Clinical Context
This dilution is commonly performed in pediatric emergency settings, as D50W is irritating to veins and dilution to 25% dextrose is desirable for safer administration 1. The American Academy of Pediatrics specifically notes that for treating hypoglycemia, D25W can be prepared by diluting D50W at a ratio of 0.5-1.0 g/kg, which corresponds to 2-4 mL/kg of the 25% solution 1.
Important Safety Considerations
- Always use sterile technique when preparing dilutions 1
- Label the final concentration clearly to prevent medication errors
- Use immediately after preparation when possible, as stability may be compromised over time 1
- Verify calculations before administration, especially in pediatric patients where dosing errors can have significant consequences 1