How to Prepare 1.5% Lidocaine Solution
To prepare 1.5% lidocaine solution, take 7.5 ml of 2% lidocaine solution and add 2.5 ml of sterile diluent (such as sterile saline or water for injection) to yield 10 ml of 1.5% lidocaine solution. 1
Detailed Preparation Method
Calculate the required volumes using the formula: C₁V₁ = C₂V₂, where:
- C₁ = Initial concentration (2%)
- V₁ = Initial volume to be determined
- C₂ = Target concentration (1.5%)
- V₂ = Final volume (10 ml) 1
For a 10 ml final volume:
- 2% × V₁ = 1.5% × 10 ml
- V₁ = (1.5% × 10 ml) ÷ 2% = 7.5 ml 1
Therefore, mix 7.5 ml of 2% lidocaine with 2.5 ml of sterile diluent 1
Important Considerations
- Use sterile technique throughout the preparation process to prevent contamination 1
- Use appropriate sterile syringes for measuring and mixing the solution 1
- Prepare the solution immediately before use for optimal efficacy 1
- Label the prepared solution clearly with:
- Medication name and concentration (1.5% lidocaine)
- Date and time of preparation
- Expiration time 1
- Refrigerate if not used immediately and discard after 24 hours 1
- Shake well before use to ensure proper mixing 1
Safety Precautions
- Always verify calculations before preparing the solution to prevent medication errors 1
- Remember that the maximum safe dose of lidocaine is 4.5 mg/kg without epinephrine and 7 mg/kg with epinephrine 1, 2
- For normal healthy adults, the maximum total dose should generally not exceed 300 mg without epinephrine 2
- Monitor for signs of lidocaine toxicity including perioral tingling, tinnitus, light-headedness, and restlessness 1
- Higher concentrations of lidocaine may be associated with more rapid onset but carry increased risk of systemic absorption 3
- Avoid concurrent use with other local anesthetics to prevent toxicity 3
Clinical Applications
- The 1.5% concentration is commonly used for local infiltration anesthesia and nerve blocks 1
- For procedures such as paracervical block during IUD insertion, lidocaine can be injected at specific sites using a 22- or 25-gauge 1.5" needle 4
By following these precise instructions, you can safely and effectively prepare a 1.5% lidocaine solution for clinical use.