Sunday, March 6, 2011

Lidocaine

It is a local anesthetic containing amide in structure.

Mechanism of action:
They act fast on sodium channels and also get detached from sodium channels rapidly. It shortens Phase 3 repolarization and blocks sodium channels and has the ability of shortening the duration of action potential.

Actions:
Due to short duration of action potential it prolongs diastole. On the other hand, it decreases the effective refractory period of purkinje fibers.

Therapeutic uses:
It is used for ventricular arrhythmias during open heart surgery, digitalis toxicity and myocardial ischemia.

It is used as local anesthesia.

Pharmacokinetics:
It undergoes first pass metabolism by the liver, so that is why it is given intravenously. In the liver, the drug is dealkalyted and approximately the entire drug is excreted by the liver.

Adverse effects:
It may cause paresthesias, hypotension, tremor, drowsiness, convulsions and respiratory arrest.

Administration and Dosage:
It is given IV with a loading dose of 150-200 mg in 15 minutes succeeded by maintenance dose of 2-4 mg/min.
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