What is the maximum dose of local anesthetics (e.g. lidocaine, bupivacaine)?

Maximum Dose of Local Anesthetics

For adults, use lidocaine up to 4.5 mg/kg (maximum 300 mg) without epinephrine or 7 mg/kg (maximum 500 mg) with epinephrine, and bupivacaine up to 2 mg/kg (maximum 175 mg) without epinephrine or 3 mg/kg (maximum 225 mg) with epinephrine. 1, 2, 3

Adult Dosing Guidelines

Lidocaine

• Without epinephrine: 4.5 mg/kg, not to exceed 300 mg total dose 1
• With epinephrine: 7 mg/kg, not to exceed 500 mg total dose 3
• For paracervical block specifically: maximum 200 mg total (100 mg per side, injected slowly with 5 minutes between sides) 1

Bupivacaine

• Without epinephrine: 2 mg/kg (approximately 175 mg for average adult) 2, 3
• With epinephrine: 3 mg/kg (approximately 225 mg for average adult) 2, 3
• Maximum single dose should not exceed 400 mg in 24 hours 2
• Doses may be repeated every 3 hours, but total daily dose should not exceed 400 mg 2

Other Common Local Anesthetics

• Mepivacaine: 7 mg/kg with epinephrine 3
• Ropivacaine: 3 mg/kg 3
• Procaine: 10 mg/kg with epinephrine 3
• Chloroprocaine: 20 mg/kg with epinephrine 3

Pediatric Dosing Guidelines

Critical modification: Reduce amide local anesthetic doses by 30% in infants younger than 6 months 3

Pediatric Maximum Doses (with epinephrine)

• Lidocaine: 7 mg/kg (medical use) or 4.4 mg/kg (dental use) 3
• Bupivacaine: 3 mg/kg (medical use) or 2.5 mg/kg (dental use) 3
• Mepivacaine: 7 mg/kg (medical use) 3
• Ropivacaine: 3 mg/kg 3

Special Pediatric Considerations

• For caudal block: 1 ml/kg of 0.25% bupivacaine (equivalent to 2.5 mg/kg) 3, 4
• Articaine should not be used in children under 4 years of age 3
• Bupivacaine is not recommended for pediatric patients younger than 12 years for general use 2

Critical Dose Adjustments

Mandatory Reductions

Reduce doses by 30% for:

• Infants younger than 6 months (amide local anesthetics only) 3
• Elderly patients 2, 3
• Debilitated patients 2, 3
• Patients with cardiac disease 2, 3
• Patients with hepatic disease 2, 3

Body Weight Considerations

• For patients weighing less than 40 kg: calculate doses carefully based on actual body weight 4, 5
• For obese patients: use ideal body weight for dose calculations 4, 5

Administration Technique to Prevent Toxicity

Pre-Administration Safety Steps

1. Calculate maximum allowable dose in mg/kg before administration to ensure patient will not receive excessive dose 3
2. Use incremental dosing: administer 3-5 mL aliquots with sufficient time between doses to detect toxic manifestations 2
3. Aspirate frequently before injection to minimize likelihood of intravascular injection 3

Monitoring Requirements

• When high doses are used, document vital signs at least every 5 minutes initially 3
• Once patient begins to awaken, recording intervals may be increased to 10-15 minutes 3
• Use lower doses when injecting into highly vascular tissues 3

Epinephrine Effects on Dosing

Adding epinephrine increases maximum safe doses by reducing systemic absorption, but this benefit is lost with inadvertent intravascular injection 3

Concentration Guidelines

• Use epinephrine in concentrations of 2.5-5 mcg/mL (typically 1:200,000) when large doses are administered 6
• Epinephrine allows higher maximum doses for most local anesthetics except when contraindicated 3

Important Caveat

Epinephrine can increase toxicity if accidentally injected intravascularly, particularly with bupivacaine and tetracaine 7. This is why frequent aspiration is critical 3.

Regional Technique-Specific Considerations

Neuraxial Administration (Epidural/Spinal)

• Bupivacaine for epidural: Use incremental doses of 3-5 mL of 0.5% solution, not exceeding 50-100 mg per dosing interval 2
• Maximum safe dose for neuraxial bupivacaine: 2.5 mg/kg (provides substantial safety margin) 8
• For intrathecal use: typical doses are much lower (7.5-25 mg bupivacaine total) 5

Intravenous Regional Anesthesia (Bier Block)

• Lidocaine dose must be reduced to 3-5 mg/kg for IV regional anesthesia 3
• Long-acting local anesthetics (bupivacaine, ropivacaine) should NOT be used for IV regional anesthesia 3
• Bupivacaine is contraindicated for IV regional anesthesia 2

Concentration Conversion Reference

Understanding concentration is essential for accurate dosing 3:

• 0.25% = 2.5 mg/mL
• 0.5% = 5 mg/mL
• 1% = 10 mg/mL
• 2% = 20 mg/mL

Local Anesthetic Systemic Toxicity (LAST) Management

Immediate Treatment Algorithm

1. Call for help and alert nearest facility with cardiopulmonary bypass capability 3
2. Ventilate with 100% oxygen and provide airway/ventilatory support 3
3. Administer 1.5 mL/kg of 20% lipid emulsion over ~1 minute for cardiovascular collapse 3
4. Initiate 20% lipid infusion at 0.25 mL/kg/min until circulation restored 3
5. For seizures: use benzodiazepines (midazolam 0.1-0.2 mg/kg IV); avoid propofol if cardiovascular instability present 3

Medications to Avoid During LAST

• Avoid vasopressin, calcium channel blockers, and β-blockers 3
• Reduce epinephrine dosages during resuscitation 3
• Prolonged resuscitation effort may be required 3

Common Pitfalls to Avoid

1. Failing to calculate maximum dose before administration: Always calculate the mg/kg dose based on patient weight before starting 3
2. Using adult doses in infants under 6 months: Remember the mandatory 30% reduction for amide local anesthetics 3
3. Rapid bolus injection: Use incremental dosing with time between doses to detect early toxicity 2
4. Ignoring highly vascular injection sites: Reduce doses when injecting into vascular areas 3
5. Combining sedatives with maximum local anesthetic doses: Enhanced sedative effects occur when highest recommended doses are combined with opioids or other sedatives 3