Reconstitution of Penicillin G 5 Million Unit Vial
To reconstitute a 5 million unit vial of Penicillin G for intravenous administration, add 8.2 mL of Sterile Water for Injection or Sterile Isotonic Sodium Chloride to achieve a concentration of 500,000 units/mL, or add 18.2 mL to achieve 250,000 units/mL 1.
Step-by-Step Reconstitution Process
Preparation technique:
- Loosen the powder in the vial first
- Hold the vial horizontally and rotate it while slowly directing the stream of diluent against the wall of the vial
- Shake the vial vigorously after all diluent has been added 1
Concentration Options for 5 Million Unit Vial
The FDA label provides specific dilution volumes 1:
| Desired Concentration | Volume of Diluent to Add |
|---|---|
| 250,000 units/mL | 18.2 mL |
| 500,000 units/mL | 8.2 mL |
For intramuscular injection: Solutions up to 100,000 units/mL can be used with minimal discomfort, though higher concentrations are physically possible 1.
For continuous IV infusion: After reconstitution, add the appropriate dose to your IV fluid (typically 1-2 liters over 12-24 hours depending on total daily dose required) 1.
Critical Storage and Stability Information
- Use Sterile Water for Injection, USP or Sterile Isotonic Sodium Chloride as diluent 1
- Avoid carbohydrate solutions at alkaline pH as penicillins are rapidly inactivated under these conditions 1
- Refrigerate all reconstituted solutions - they remain stable for 7 days when refrigerated 1
- Research confirms stability of diluted penicillin G (2,500-50,000 units/mL) in 0.9% sodium chloride or 5% dextrose stored at 5°C in PVC containers for at least 21 days 2
Important Caveats
The 5 million unit vial can be used for either intramuscular or intravenous administration, unlike the 20 million unit vial which is for IV infusion only 1. If the required volume of solvent exceeds vial capacity, dissolve with a portion of diluent first, withdraw the solution, and combine with remaining diluent in a larger sterile container 1.