Lidocaine

This anti-arrhythmic agent suppresses automaticity of conduction and spontaneous depolarisation of the ventricles during diastole. Clearance is related to both hepatic blood flow and hepatic function; it will be prolonged in liver disease, cardiac failure and the elderly.The effects after the initial bolus dose last about 20 min.An IV infusion is needed to maintain the anti-arrhythmic effect.

Uses
Prevention of ventricular ectopic beats,VT and VF after MI

Contraindications
It is no longer the first-line drug in pulseless VT or VF during cardiac arrest
Hypersensitivity to amide-type local anaesthetics (rare)
Heart block (risk of asystole)

Administration
• Loading dose:
  1.5 mg/kg IV over 2 min, repeat after 5 min to a total dose of
  3 mg/kg if necessary. Reduce dose in the elderly
• Maintenance dose:
  4 mg/min for 1st hour
  2 mg/min for 2nd hour
  1 mg/min thereafter

Reduce infusion rates in patients with hepatic impairment, cardiac failure and in the elderly
Undiluted 40 ml 2% solution (800 mg)
4 mg/min = 12 ml/h
2 mg/min = 6 ml/h
1 mg/min = 3 ml/h
Continuous ECG and BP monitoring

How not to use lidocaine
Do not give by rapid IV bolus (should not be given at >50 mg/min)

Adverse effects
Paraesthesia,muscle twitching, tinnitus
Anxiety, drowsiness, confusion, convulsions
Hypotension, bradycardia, asystole

Cautions
Elderly (reduced volume of distribution, reduce dose by 50%)
Hepatic impairment
Cardiac failure
Other class 1 anti-arrhythmics, e.g. phenytoin, may increase risk of toxicity

Organ failure
Cardiac: reduce dose
Hepatic: reduce dose