What is the recommended dosage and administration guidelines for intravenous (IV) lignocaine (lidocaine) use?

Intravenous Lignocaine (Lidocaine) Administration

For ventricular arrhythmias, administer an initial IV bolus of 1 mg/kg (maximum 100 mg) over 2 minutes, followed by additional 0.5 mg/kg boluses every 5-10 minutes if needed (total maximum 3 mg/kg or 200 mg), then maintain with continuous infusion at 2-4 mg/min. 1 For perioperative analgesia, use ideal body weight to calculate a loading dose of 1.5 mg/kg infused over 10 minutes, followed by maintenance infusion of 1.5 mg/kg/hour for maximum 24 hours. 2

Cardiac Arrhythmia Indications and Dosing

Ventricular Tachycardia with Pulse

• Initial bolus: 50 mg IV over 2 minutes, repeated every 5 minutes to total dose of 200 mg 1
• Alternative dosing: 1-3 mg/kg IV bolus (1 mg/kg initial, then 0.5 mg/kg every 8-10 minutes to maximum 4 mg/kg) 1
• Maintenance infusion: 2-4 mg/min (20-50 µg/kg/min) once rhythm controlled 1
• Lignocaine is the first-choice antiarrhythmic for ventricular tachycardia 1

Ventricular Fibrillation/Pulseless VT

• Cardiac arrest dosing: 100 mg bolus, may repeat after 5-10 minutes 1
• Only use after failed defibrillation attempts (after 12 DC shocks with appropriate advanced life support) 1

Acute Myocardial Infarction Context

• Use for frequent ventricular ectopy (>6/min), closely coupled beats (R-on-T), multiform configuration, or runs of 3+ beats 1
• Loading: 1 mg/kg IV bolus (not exceeding 100 mg), then 0.5 mg/kg every 8-10 minutes if needed 1
• Maintenance: 20-50 µg/kg/min (1.4-3.5 mg/min in 70 kg patient) 1
• A second 0.5 mg/kg bolus may be needed at 30-120 minutes after initiation to maintain therapeutic levels 1

Perioperative Analgesia Dosing (Modern Guidelines)

This represents a fundamentally different dosing paradigm than cardiac use, with significantly lower doses and stricter safety protocols. 2

Loading and Maintenance

• Loading dose: 1.5 mg/kg (using ideal body weight) infused over 10 minutes—never as bolus 2
• Maintenance: 1.5 mg/kg/hour, maximum 120 mg/hour regardless of weight 2
• Duration limit: 24 hours maximum 2
• Weight restriction: Do not use in patients <40 kg 2

Critical Safety Requirements for Analgesic Use

• Anesthesiologist must be present during loading dose administration 2
• Continuous ECG monitoring, pulse oximetry, and regular blood pressure measurements required 2
• Administer through dedicated, separate IV cannula 2
• Timing restriction: Do not use within 4 hours of other local anesthetic interventions (nerve blocks) 2
• Do not perform nerve blocks until 4 hours after discontinuing infusion 2
• Lipid emulsion 20% must be immediately available 2

Pharmacokinetic Considerations and Dose Adjustments

Half-Life Changes Over Time

• Short infusions (<12 hours): Half-life 100 minutes 2
• 24-hour infusions: Half-life increases to 3.22 hours 2
• After 24 hours: Reduce infusion rate by 50% even without cardiac/hepatic failure 2
• In uncomplicated MI: Half-life >4 hours 1
• In heart failure: Half-life >20 hours 1
• In cardiogenic shock: Even longer half-life, requiring substantial dose reduction 1

Factors Increasing Toxicity Risk

• Acidemia: Increases free drug by enhancing dissociation from plasma proteins 2
• Hypoalbuminemia: Increases free plasma concentration 2
• Low skeletal muscle mass: Reduces drug reservoir capacity 2
• High BMI: Using actual vs. ideal body weight causes inadvertently higher plasma levels 2
• Beta-blockers: Reduce lignocaine metabolism 2
• Amiodarone: Decreases clearance, particularly problematic with prolonged infusions 2
• Cytochrome P450 modulators: Affect metabolism 2

Maximum Dosing Limits by Clinical Context

Cardiac Use (FDA-Approved)

• With epinephrine: Maximum 7 mg/kg (3.5 mg/lb), generally not exceeding 500 mg total 3
• Without epinephrine: Maximum 4.5 mg/kg (2 mg/lb), generally not exceeding 300 mg total 3
• Continuous epidural/caudal: Maximum dose should not be repeated at intervals <90 minutes 3
• IV regional anesthesia (Bier block): Maximum 4 mg/kg in adults 3

Pediatric Dosing

• Children >3 years: 1.5-2 mg/kg (0.68-0.9 mg/lb) maximum 3
• Infants <6 months: Reduce all amide local anesthetic doses by 30% 4
• Use lowest effective concentration (0.25-0.5%) for IV regional anesthesia, not exceeding 3 mg/kg 3

Administration Technique

Delivery Route

• All drugs for life-threatening arrhythmias must be given IV 1
• Peripheral IV drugs should be followed by 20 mL saline bolus to aid central circulation delivery 1
• If no venous access: Endotracheal route possible (double or triple doses), particularly for adrenaline 1

Avoiding Subtherapeutic Intervals

• Patients requiring multiple boluses to suppress ectopy likely need higher maintenance doses (up to 40-50 µg/kg/min) 1
• If arrhythmia recurs after 8-10 hours at steady infusion, give additional bolus and increase maintenance rate 1
• Simply increasing infusion rate without bolus takes >6 hours to reach new plateau 1

Toxicity Recognition and Management

Toxic Plasma Concentration

• Toxicity occurs at 9-10 µg/mL 2
• Therapeutic range: Up to 5 µg/mL 1

Early Warning Signs

• Perioral numbness, facial tingling 4
• Tinnitus, metallic taste 2, 4
• Visual disturbances 2
• Circumoral pallor 4

Progressive Toxicity

• Drowsiness, confusion 1, 2
• Muscular twitching, paraesthesia 1
• Seizures 1, 2
• Cardiovascular collapse 2

Management

• Lipid emulsion 20% should be readily available and administered for systemic toxicity 2
• In epidural overdose with catheter in place, consider draining moderate amount (10 mL) of CSF through catheter 3

Common Pitfalls and How to Avoid Them

Dosing Errors

• Using actual vs. ideal body weight: Always use ideal body weight for analgesic infusions, especially in obese patients 2, 4
• Concentration confusion: 1% lignocaine = 10 mg/mL; calculate total mg before administering 4
• Cumulative dosing: Track total dose over time in prolonged procedures 4

Drug Interactions

• Concurrent local anesthetics: Account for additive effects when multiple agents used 4
• Timing with nerve blocks: Maintain 4-hour separation between IV lignocaine and regional techniques 2
• Enhanced sedation: Maximum doses combined with opioids/sedatives cause enhanced sedative effects 4

Clinical Context Errors

• Cardiac failure/shock: Dramatically reduce doses due to prolonged half-life 1
• Elderly/debilitated: Reduce doses 3
• Liver disease: Reduce doses due to decreased metabolism 1, 3
• After 12-24 hours: Reduce infusion by 1 mg/min at 12 hours or at least by 24 hours 1

Monitoring Failures

• Lignocaine depresses myocardial contractility—monitor hemodynamics closely 1
• No effect on supraventricular tachycardia—do not use for SVT 1
• Increased incidence of asystole reported with lignocaine use 1