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