Lignocaine (Lidocaine) - Antiarrhythmic Cardiovascular Poison

 Lignocaine (Lidocaine)

·              Lignocaine is an aminoacyl amide, and is a synthetic derivative of cocaine. It is used as an anaesthetic agent as well as antiarrhythmic agent. It is effective in controlling ventricular arrhythmias.

Toxicokinetics

Lignocaine is generally given intravenously, and is 50% bound to protein with an apparent volume of distribution of 1.3 L/ kg in adults. It is metabolised in the liver to monoethylgly-cinexylidide (MEGX) which is active pharmacologically, and subsequently to inactive compounds which are excreted mainly in the urine.

Adverse Effects and Clinical (Toxic) Features

·      Blood levels of more than 5 mcg/ml are associated with serious toxicity, and more than 15 mcg/ml with death.

·      Vertigo, drowsiness, confusion, ataxia, dysarthria, hearing loss, visual disturbances, agitation, fasciculations, convul-sions, cardiovascular collapse, and coma.

·              Massive overdose can produce rapid onset of hypotonia, apnoea, and asystole. Even after recovery, symptoms can persist for a prolonged period because of persistent metabo-lites.

Treatment

·      Diazepam for convulsions.

·      Fluids, dopamine, adrenaline, atropine, and cardiac pacing as necessary.

·      Extracorporeal pump may help in severe overdose.

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