Recommended Dosage of Lignocaine 2% With and Without Adrenaline for Local Infiltration
For a 70 kg adult undergoing local infiltration anesthesia, the maximum safe dose is 315 mg (15.75 mL) of lignocaine 2% without adrenaline, or 490 mg (24.5 mL) of lignocaine 2% with adrenaline. 1, 2
Adult Dosing Guidelines
Lignocaine 2% Without Adrenaline
- Maximum dose: 4.5 mg/kg 1, 2
- For a 70 kg adult: 4.5 mg/kg × 70 kg = 315 mg total 1
- Volume calculation: 315 mg ÷ 20 mg/mL = 15.75 mL of 2% solution 1
- The FDA recommends not exceeding 300 mg total dose in general practice 2
Lignocaine 2% With Adrenaline (Epinephrine)
- Maximum dose: 7.0 mg/kg 1, 2
- For a 70 kg adult: 7.0 mg/kg × 70 kg = 490 mg total 1
- Volume calculation: 490 mg ÷ 20 mg/mL = 24.5 mL of 2% solution 1
- The FDA recommends not exceeding 500 mg total dose in general practice 2
Key Clinical Advantages of Adding Adrenaline
Adding adrenaline to lignocaine provides significant clinical benefits beyond just allowing higher doses: 3, 4
- Prolongs duration of anesthesia by approximately 200% 4
- Slows systemic absorption, reducing peak blood levels and toxicity risk 4
- Improves surgical field visualization through vasoconstriction 4
- Standard concentrations used are 1:100,000 or 1:200,000 3, 5
Critical Safety Measures to Prevent Toxicity
Always implement these steps when administering local infiltration anesthesia: 1
- Use the lowest effective dose for the procedure 1, 2
- Aspirate before each injection to avoid intravascular administration 1, 2
- Use incremental injections rather than bolus administration 1, 2
- Continuously monitor the patient for early toxicity signs (circumoral numbness, facial tingling, slurred speech, metallic taste) 1, 3
Important Clinical Caveats
Concentration Considerations
- 2% lignocaine (20 mg/mL) should be used cautiously for infiltration 6
- More dilute solutions (0.4-0.5%) allow safer use of higher total volumes when extensive infiltration is needed 6
- The 2% concentration is appropriate for smaller volume infiltrations where the total dose remains within safe limits 6
Site-Specific Factors
- Regional blood flow significantly affects absorption rates 7
- Areas with high vascularity (face, scalp, highly vascular tissues) require dose reduction due to faster systemic absorption 7, 8
- Well-vascularized sites may absorb lignocaine more rapidly, increasing toxicity risk even at standard doses 7
Cardiovascular Considerations
- When adrenaline is added, expect transient increases in heart rate and blood pressure 5
- For patients with cardiac disease, consider using 1:200,000 adrenaline concentration instead of 1:100,000 to minimize cardiovascular effects 5
- The cardiovascular effects are typically short-lived but should be monitored 5
Special Populations Requiring Dose Reduction
Reduce doses by 30-50% in the following situations: 2, 8
- Elderly or debilitated patients 2
- Patients with cardiac disease 2, 8
- Patients with hepatic dysfunction (reduced clearance) 8
- Patients with renal disease 8
- Pediatric patients (maximum 1.5-2.0 mg/kg without adrenaline; 3.0-4.5 mg/kg with adrenaline) 1, 3
Multistage Procedures
For procedures requiring multiple injections over time (e.g., Mohs surgery): 1, 3