Chalocaine Viscous Solution Mechanism of Action

Pharmacology: Pharmacodynamics: Chalocaine Viscous Solution contains Lidocaine, the amide type local anaesthetics. Lidocaine blocks conduction of the impulse through nerve fiber by decreasing the cell membrane permeability to sodium ions, thereby effecting local anesthetic action. Surface or topical anaesthetics blocks the sensory nerve endings in the skin or mucous membrane.
Lidocaine has a rapid onset with an intermediate duration of action. Onset and the duration of the local anesthetic effect of lidocaine depend on the dose and the site of administration.
Pharmacokinetics: Absorption: Following topical administration Lidocaine is absorbed from mucous membrane and through damaged skin. The plasma concentration of Lidocaine depends upon the dose, the route of administration and the site of administration.
Serum Lidocaine concentrations were usually so low as to be unmeasurable in patients who gargled and expectorated 15 mL (300 mg) of a 2% viscous solution before endoscopy.
Distribution: Lidocaine is bound to plasma proteins (mainly to alpha1-acid glycoprotein) the extent of binding is about 60-80%. The plasma binding of Lidocaine is dependent on drug concentration.
Lidocaine crosses the placenta and blood-brain barrier also is distributed breast milk.
Metabolism: Lidocaine is rapidly metabolized in the liver by de-ethylation. The active metabolites formed from Lidocaine are monoethylglycinexylidide (MEGX) and glycinexylidide (GX) which can accumulate and may cause CNS toxicity.
Excretion: Lidocaine has a terminal half-life of 1.5-2 hours. Half-life elimination may also be decreased in patients congestive heart failure or liver disease. May be prolonged lasting longer than 24 hours.
Metabolites and unchanged drug are excreted by the kidneys, metabolites are excreted in the urine with less than 10% of unchanged.