What is the recommended route of administration for Lignocaine (Lidocaine)?

Recommended Route of Administration for Lignocaine (Lidocaine)

Lignocaine should be administered intravenously for life-threatening cardiac arrhythmias, with intramuscular injection reserved only as an alternative when IV access is unavailable, and subcutaneous administration is appropriate solely for local anesthesia purposes. 1

Route Selection Based on Clinical Indication

For Cardiac Arrhythmias (Life-Threatening)

• Intravenous (IV) is the mandatory first-line route for ventricular tachycardia and ventricular fibrillation 1
• Administer 1-3 mg/kg IV, or 100 mg bolus for cardiac arrest, which may be repeated after 5-10 minutes 1
• If successful cardioversion occurs, maintain plasma levels with IV infusion of 2-4 mg/min 1
• Intramuscular (IM) injection can achieve sustained therapeutic levels but is often associated with early minor toxicity and is not the preferred route 2
• IM administration of high doses results in sustained therapeutic levels but should only be used when IV access is impossible 2

For Local Anesthesia

• Subcutaneous and infiltration techniques are appropriate for local anesthetic purposes 3
• Maximum dose without epinephrine: 4.5 mg/kg (not to exceed 300 mg total in adults) 3
• Maximum dose with epinephrine: 7 mg/kg (not to exceed 500 mg total in adults) 3
• For epidural anesthesia, lignocaine is administered via the epidural space, not subcutaneously or intramuscularly 4

For Specialized Applications

• Intrapleural administration is recommended at 3 mg/kg (maximum 250 mg) just prior to sclerosant administration for pleurodesis 1
• Endotracheal route may be used for cardiac arrest when no venous access is possible, using double or triple the IV dose 1
• Topical/nebulized routes are appropriate for bronchoscopy and airway procedures, with maximum dose of 8.2 mg/kg in adults 1

Critical Safety Considerations

IV Administration Requires Specific Protocols

• Calculate dose using ideal body weight, not actual body weight, especially in obese patients 5, 6
• Loading dose should not exceed 1.5 mg/kg, administered as an infusion over 10 minutes (never as a bolus) 5, 6
• Maintenance infusion should not exceed 1.5 mg/kg/hour or 120 mg/hour regardless of weight 5
• Continuous ECG monitoring, pulse oximetry, and regular blood pressure measurements are mandatory during IV administration 5
• Deliver through a separate, dedicated cannula 6

Contraindications to Specific Routes

• Do not use IV lignocaine in patients weighing less than 40 kg 5, 6
• Do not administer IV lignocaine within 4 hours of other local anesthetic interventions (e.g., nerve blocks) 5, 6
• Remove topical lidocaine patches before starting IV infusion 7

Common Pitfalls to Avoid

Dosing Errors

• The maximum recommended doses are frequently exceeded in clinical practice, but studies show that up to 900 mg with adrenaline for brachial plexus block can be safe without toxic symptoms 8
• However, toxic blood levels (>5 mg/L) can occur, and the maximum dose of 8.2 mg/kg suggested for bronchoscopy is higher than the <3 mg/kg recommended for infiltration 1
• In children over 3 years, do not exceed 3 mg/kg for dilute solutions (0.25-0.5%) 3

Drug Interactions

• Cimetidine significantly increases plasma lignocaine concentrations compared to famotidine or no H2-blocker, making famotidine preferable when epidural lignocaine is used 4
• Beta-blockers reduce lignocaine metabolism, and amiodarone decreases clearance, both increasing toxicity risk 5

Clinical State Considerations

• IV lignocaine administered to blunt extubation responses can result in toxic reactions (including generalized convulsions) depending on the patient's clinical and physiological state, even within recommended doses 9
• In cardiac failure, lignocaine clearance is reduced and blood concentrations may continue to rise for 24-48 hours, requiring dose reduction 2
• Hepatic disease reduces clearance and requires dose adjustment 2

Timing Issues

• With constant IV infusion, steady-state concentrations are reached after 3-4 hours in normal subjects and 8-10 hours in myocardial infarction patients without circulatory insufficiency 2
• Current bolus-then-infusion practices may create a subtherapeutic interval between peak serum level and steady state; continuous infusion at 25 mg/min (weight-based dosing) eliminates this gap 10