It is a class 1 antiarrhythmic drug (subgroup 1 A) Indications: ventricular arrhythmias, especially after myocardial infarction. (Also used as a local anaesthetic).

Cautions: lower dose in congestive cardiac failure, and following cardiac surgery; in elderly and in hepatic and renal impairment.

Contra-indications: sino-atrial disorders, all grades of AV block; severe myocardial depression; porphyria

Side Effects: dizziness; parasthesia or drowsiness; CNS effects like confusion, respiratory depression & convulsions; hypotension and bradycardia; rarely anaphylaxis.

Dose: by IV injection, in patients without gross circulatory impairment, 100 mg as a bolus over a few minutes as a loading dose, followed by infusion of 4 mg/minute for 30 minutes, 2 mg/minute for 2 hours, then 1 mg/minute; reduce infusion rate if infusion is continued beyond 24 hours. ECG monitoring is required.