Friday January 2, 2009


Case: 52 year old male is admitted with frequent runs of ventricular tachycardia and was started on IV Lidocaine with 2mg/min drip. First lidocaine serum level is 8.5 micrograms/ml. To determine the time period to shut off Lidociane drip, do you know the half life of intravenous Lidocaine?

Answer: The elimination half-life of lidocaine is approximately 1.5–2 hours in most patients. But it may be prolonged in patients with liver insufficiency upto 6-8 hours. Also, in patients with congestive heart failure, it may be slightly prolonged upto 3 hours. Though Lidociane is excreted via urine but renal insufficiency doesn't effects its level much as 90% Lidocaine is metabolized in the liver by to the pharmacologically-active metabolites.

Lidocaine alters depolarization in neurons, by blocking sodium (Na+) channels in the cell membrane, leading to its anaesthetic effects. And toxic dosage may lead to nervousness, tingling, tinnitus, tremor, dizziness, blurred vision and seizures.

In above case, it would be appropriate to hold Lidocaine drip for 4-6 hours and drew the level again to determine the rate of infusion.