Recommendations for Using Lidocaine and Prilocaine for Local Anesthesia
For local anesthesia procedures, lidocaine and prilocaine should be administered according to specific dosing guidelines with maximum doses of 4.5 mg/kg for lidocaine without epinephrine, 7.0 mg/kg with epinephrine, and using ideal body weight for calculations to ensure safety and efficacy. 1
Dosing and Administration Guidelines
Lidocaine Administration
- Maximum safe dose: 4.5 mg/kg without epinephrine, 7.0 mg/kg with epinephrine for adults 1
- For intravenous lidocaine: Initial dose should not exceed 1.5 mg/kg based on ideal body weight, given over 10 minutes 2
- For IV infusion: Maximum 1.5 mg/kg/h for no longer than 24 hours 2
- Calculate using ideal body weight (men: height in cm - 100; women: height in cm - 105) 1
- For multistage procedures like Mohs surgery: Maximum 500 mg (50 mL of 1% solution) 1
Prilocaine/Lidocaine Combination (EMLA Cream)
- Apply a thick layer (1-2 g/10 cm²) for optimal effect 3
- Application times vary by procedure:
- Venipuncture: 1 hour application
- Split thickness skin grafts: 2 hours application
- Genital mucous membranes: 5-15 minutes (optimal analgesia achieved in this timeframe) 3
Pediatric Dosing
- Children under 7 years: Less effective than in older children 3
- Neonates: Use with caution due to risk of methemoglobinemia 3
- Maximum doses based on age and weight:
- 0-3 months or <5 kg: 1g over 10 cm² for 1 hour
- 3-12 months and >5 kg: 2g over 20 cm² for up to 4 hours
- 1-6 years and >10 kg: 10g over 100 cm² for up to 4 hours
- 7-12 years and >20 kg: 20g over 200 cm² for up to 4 hours 3
Safety Considerations
Drug Interactions and Timing
- Do not use IV lidocaine within 4 hours of nerve blocks 2
- Do not perform nerve blocks until 4 hours after discontinuing IV lidocaine infusion 2
- Remove topical lidocaine patches before starting IV lidocaine infusion 1
- When using multiple forms of local anesthesia simultaneously, consider total dose to avoid toxicity 1
Use with Vasoconstrictors
- Epinephrine is safe and recommended for use on the ear, nose, hand, feet, and digits 2
- Use the lowest effective concentration of epinephrine (common concentrations: 1:100,000 and 1:200,000) 1
- Small amounts of lidocaine with epinephrine appear safe in patients with stable cardiovascular disease 1
- For uncertain cases, consult with the patient's cardiologist 2
Special Populations
- Pregnant women: Elective procedures requiring lidocaine with epinephrine should be postponed until after delivery 2
- Urgent procedures should be delayed until the second trimester when possible 2
- Consult with the patient's obstetrician in case of doubt 2
Optimizing Anesthetic Effect
Buffering
- Adding sodium bicarbonate to local anesthetic, particularly lidocaine with epinephrine, is recommended to decrease pain during infiltration 2
- Alkalinized lidocaine solution has proven significantly superior to lidocaine only for certain procedures 4
- Preinjection of buffered lidocaine solution is suggested to reduce the pain of bupivacaine infiltration 2
Combination Approaches
- Lidocaine and prilocaine cream followed by lidocaine infiltration is more effective than either alone for certain procedures 3
- For genital mucous membranes, 5-10g of lidocaine and prilocaine cream applied 5-15 minutes before surgery provides effective local anesthesia 3
Monitoring for Toxicity
- Early symptoms of lidocaine toxicity: circumoral numbness, facial tingling, slurred speech, metallic taste, and auditory changes 1
- Severe cases can lead to seizures, CNS depression, and cardiac complications 1
- Use the lowest effective dose and continuously monitor patients during procedures 1
- True lidocaine allergy is rare (approximately 1% of adverse reactions) 1
By following these guidelines, clinicians can safely and effectively use lidocaine and prilocaine for local anesthesia across a variety of procedures while minimizing risks and optimizing patient comfort.