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Antiarrhythmic Pregnancy: Use with caution — crosses placenta; neonatal toxicity possible. Short-term IV for maternal arrhythmia acceptable under specialist supervision.

Lidocaine IV (Cardiac Arrhythmia)

Brand names: Xylocard

Adult dose

Dose: Loading: 1-1.5 mg/kg IV bolus over 2 minutes. Maintenance infusion: 1-4 mg/min. Additional boluses: 0.5-0.75 mg/kg if arrhythmia recurs (max 3 mg/kg total in first hour).
Route: Intravenous
Frequency: Loading bolus then continuous infusion
Max: 3 mg/kg total loading; 4 mg/min infusion
Class Ib antiarrhythmic. Alternative to amiodarone for refractory VT/VF when amiodarone unavailable (ERC 2021). Hepatic flow-dependent clearance — reduce infusion rate in HF/elderly.

Paediatric dose

Dose: 1 mg/kg
Route: IV bolus over 2 minutes
Frequency: Loading, then infusion 25-50 mcg/kg/min
Max: 3 mg/kg total loading
Cardiac arrest (paediatric): 1 mg/kg IV/IO if amiodarone unavailable.

Dose adjustments

Renal

No adjustment for short-term use; prolonged infusion in severe renal impairment — monitor for toxic metabolite accumulation

Hepatic

Reduce infusion dose 50% in severe hepatic impairment — extensively hepatically metabolised

Paediatric weight-based calculator

Cardiac arrest (paediatric): 1 mg/kg IV/IO if amiodarone unavailable.

Clinical pearls

  • ERC 2021: amiodarone 300 mg is FIRST-LINE after 3 shocks in VF/pulseless VT. Lidocaine 100 mg is the ALTERNATIVE if amiodarone unavailable — not the preferred agent.
  • CNS toxicity sequence: perioral tingling/metallic taste (early warning) → dizziness → confusion → seizures → coma. Reduce infusion rate at first sign.
  • Hepatic flow dependency: in acute MI with reduced cardiac output, hepatic blood flow falls — lidocaine accumulates rapidly even at standard doses. Use lowest effective rate.
  • Lipid emulsion antidote (Intralipid 20%): for severe local anaesthetic toxicity — 1.5 mL/kg IV bolus. AAGBI protocol.
  • Standard prep: 500 mg in 500 mL 5% glucose = 1 mg/mL. Rate 1 mL/min = 1 mg/min.

Contraindications

  • Sino-atrial disorder
  • All degrees of AV block (without pacemaker)
  • Wolff-Parkinson-White syndrome
  • Severe heart failure (extreme caution)

Side effects

  • CNS toxicity — progressive: dizziness, perioral numbness, confusion, seizures, coma
  • Cardiac conduction depression (toxic doses)
  • Hypotension
  • Respiratory depression

Interactions

  • Beta-blockers — additive cardiac conduction depression
  • Cimetidine/propranolol — reduce lidocaine clearance; increase toxicity risk

Monitoring

  • Continuous ECG
  • Blood pressure
  • CNS signs (confusion, drowsiness)
  • Lidocaine plasma levels if prolonged infusion (therapeutic: 1.5-5 mcg/mL)

Reference: BNFc; BNF 90; ERC Resuscitation Guidelines 2021; AAGBI Local Anaesthetic Toxicity Guidelines; SPC Xylocard. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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