What is the maximum dosage of a 2% solution of lidocaine with epinephrine (adrenaline)?

Maximum Dosage of 2% Lidocaine with Epinephrine

For adults undergoing local infiltrative anesthesia, the maximum safe dose of 2% lidocaine with epinephrine is 7 mg/kg (not to exceed 500 mg in most cases), which translates to 0.35 mL/kg or approximately 24.5 mL for a 70 kg patient. 1, 2, 3

Dose Calculation for 2% Lidocaine Solution

Understanding the concentration: 2% lidocaine = 20 mg/mL 2

Maximum volume calculation:

• Adults: 7 mg/kg ÷ 20 mg/mL = 0.35 mL/kg maximum volume 1, 2
• Children: 3.0-4.5 mg/kg ÷ 20 mg/mL = 0.15-0.225 mL/kg maximum volume 1, 2

Adult Dosing Guidelines

Standard local infiltration with epinephrine:

• Maximum dose: 7 mg/kg 1, 2, 3
• Absolute maximum: 500 mg (25 mL of 2% solution) for single-stage procedures 2, 3
• FDA-approved maximum: 4.5 mg/kg without epinephrine (300 mg absolute maximum) 4

The addition of epinephrine increases the safe dose by 55% (from 4.5 to 7 mg/kg) by decreasing systemic absorption through vasoconstriction. 1, 2

For prolonged or multistage procedures (e.g., Mohs surgery):

• Maximum 500 mg delivered incrementally over 8 hours is safe 1, 2
• This allows for higher total doses when administered gradually with adequate time intervals 1

Pediatric Dosing Guidelines

Children require substantially lower doses:

• With epinephrine: 3.0-4.5 mg/kg 1, 2
• Without epinephrine: 1.5-2.0 mg/kg 1, 2

Critical adjustment for infants under 6 months:

• Reduce all amide local anesthetic doses by 30% 2, 3
• Example: For a 6-month-old, maximum with epinephrine = 3.15 mg/kg (70% of 4.5 mg/kg) 2

Critical Safety Measures

Before administering, always:

• Calculate the maximum allowable dose in milligrams based on patient weight 1, 2, 3
• Use ideal body weight for obese patients, not actual body weight 2, 3
• Aspirate before each injection to avoid intravascular administration 1, 3

Dose reduction required in:

• Highly vascular areas (increased systemic absorption) 2, 3
• Elderly patients (altered pharmacokinetics) 3
• Patients with hepatic or cardiac impairment 2

Monitoring for Toxicity

Early warning signs of local anesthetic systemic toxicity (LAST):

• Circumoral numbness and facial tingling 1, 3
• Metallic taste 1, 3
• Tinnitus and auditory changes 1, 3
• Slurred speech or pressured speech 1

Progressive toxicity:

• Seizures or CNS depression 2, 3
• Cardiac arrhythmias and cardiovascular collapse 3

Monitoring requirements:

• Document vital signs every 5 minutes initially, then every 10-15 minutes once stable 2, 3
• Maintain continuous patient communication throughout the procedure 1, 3

Common Pitfalls and How to Avoid Them

Calculation errors:

• Remember: 2% = 20 mg/mL, not 2 mg/mL 2
• Always convert percentage to mg/mL before calculating volumes 2

Cumulative dosing mistakes:

• Track total dose administered over time in prolonged procedures 2, 3
• Account for additive effects when using multiple local anesthetics 2, 3

Using actual body weight in obese patients:

• This leads to overdosing; always use ideal body weight 2, 3

Bolus administration:

• Use incremental injections rather than large boluses to minimize peak serum levels 1, 3

Special Considerations for Epinephrine Concentration

The concentration of epinephrine in the solution does not affect the maximum lidocaine dose calculation. 5

• Standard concentrations range from 1:80,000 to 1:200,000 5
• Lower epinephrine concentrations (1:200,000) provide better hemodynamic stability without compromising anesthetic efficacy 5
• For large-volume infiltration, concentrations of 2.5-5 μg/mL epinephrine are recommended 1