Xylocaine Jelly Mechanism of Action

Pharmacotherapeutic Group: Local anaesthetic. ATC Code: N01BB02.
Pharmacology: Xylocaine Jelly provides prompt and profound anaesthesia of mucous membranes and lubrication which reduces friction. Its water-miscible base, characterized by high viscosity and low surface tension, brings the anaesthetic into intimate and prolonged contact with the tissue, giving effective anaesthesia of long duration (approximately 20-30 min). Anaesthesia usually occurs rapidly (within 5 min, depending upon the area of application).
Lidocaine, like other local anaesthetics, causes a reversible blockade of impulse propagation along nerve fibres by preventing the inward movement of sodium ions through the nerve membrane. Local anaesthetics of the amide type are thought to act within the sodium channels of the nerve membrane.
Local anaesthetic drugs may also have similar effects on excitable membranes in the brain and myocardium. If excessive amounts of the drug reach the systemic circulation rapidly, symptoms and signs of toxicity will appear, emanating from the central nervous and cardiovascular systems.
Central nervous system toxicity (see Overdosage) usually precedes the cardiovascular effects as it occurs at lower plasma concentrations. Direct effects of local anaesthetics on the heart include slow conduction, negative inotropism and possibly cardiac arrest.
Pharmacokinetics: Absorption from the mucous membranes is variable but especially high from the bronchial tree. The absorption of lidocaine jelly from the nasopharynx is usually lower than with other lidocaine products. Blood concentrations of lidocaine after instillation of the jelly in the intact urethra and bladder in doses up to 800 mg are fairly low and below toxic levels.