Recommended Dosing of Lidocaine for Local Anesthesia and Systemic Use
The maximum recommended dose of lidocaine for local anesthesia is 4.5 mg/kg (2 mg/lb) body weight without epinephrine, and 7 mg/kg (3.2 mg/lb) body weight with epinephrine, with a total dose not exceeding 300 mg in adults. 1
Local Anesthesia Applications and Dosing
Topical Application
- For laryngoscopy, bronchoscopy, and endotracheal intubation:
- 1-5 mL of 4% lidocaine (40-200 mg) may be sprayed on the pharynx 1
- This equals approximately 0.6-3 mg/kg or 0.3-1.5 mg/lb body weight
Injectable Local Anesthesia
- Retrobulbar injection: 3-5 mL (120-200 mg) for a 70 kg person 1
- Transtracheal injection: 2-3 mL, rarely requiring more than 5 mL (200 mg) 1
Topical Lidocaine Preparations
- 4% topical lidocaine gel shows significant anesthetic effect without occlusion in approximately 25-30 minutes 2
- Optimal effects are observed between 35-40 minutes after application 2
- Caution: Occlusive dressings can triple serum lidocaine levels compared to non-occlusive application 3
Systemic (Intravenous) Lidocaine Administration
Dosing Guidelines
- Loading dose: Not exceeding 1.5 mg/kg over 10 minutes 4
- Infusion rates: Not exceeding 1.5 mg/kg/h 4
- Use ideal body weight rather than actual body weight when calculating doses 4
Safety Protocols for IV Administration
- Requires strict protocols including:
- Dedicated cannulas with minimum flow of sodium chloride 0.9% at 10 ml/h
- One-way valves
- Continuous ECG monitoring
- Regular vital sign checks 4
- Lipid emulsion 20% must be readily available for toxicity treatment 4
Special Populations
Pediatric Dosing
- For children under 10 years: Calculate using pediatric drug formulas (e.g., Clark's rule) 1
- Example: For a 5-year-old weighing 50 lbs, maximum dose should not exceed 75-100 mg 1
- Children under 12 months or weighing less than 10 kg require lower doses 4
- Patients weighing less than 40 kg are contraindicated for IV lidocaine infusions 4
Elderly and Debilitated Patients
- Dosages should be reduced for elderly and debilitated patients 1
- Use the lowest effective dose to minimize risk of toxicity
Contraindications and Precautions
Absolute Contraindications
- Active infections
- True lidocaine allergy
- Uncontrolled diabetes
- Severe hypertension
- Heart failure
- Neurological disorders 4
Relative Contraindications
- Cardiac disease
- Electrolyte disorders
- Seizure disorders
- Renal or hepatic impairment
- Pregnancy/breastfeeding 4
Monitoring and Toxicity Prevention
- Monitor for early signs of toxicity: circumoral numbness, facial tingling, light-headedness, and tinnitus 4
- For IV administration: Continuous ECG, pulse oximetry, and regular blood pressure monitoring 4
- Significant interindividual variability exists in lidocaine metabolism, requiring careful monitoring 3
- Although rare, anaphylactic reactions to lidocaine can occur and require immediate treatment 5
Important Considerations
- The incidence of adverse effects is directly proportional to the total dose administered 1
- Doubling the dose of 4% lidocaine from 2.5g to 5g can result in double the serum levels of MEGX (lidocaine metabolite) and a 50% increase in serum lidocaine levels 3
- When using lidocaine with epinephrine in digits, be aware of the risk of epinephrine-induced vasospasm; phentolamine should be available as a rescue medication 6