Action of Some Selected Local Anaesthetics

The specific mode of action of certain local anaesthetics, already discussed under Section 4.2, are enumerated below  

The onset of action is found to be rather slow but it is of relatively longer duration. It is normally hydrolyzed by plasma esterases to/lara-aminobenzoic acid (PABA) together with some other metabolites. Due to its inherent high level of toxicity it is invariably being employed for several restricted topical applications , for instance bronchoscopy, ENT-related surgieal proeedures, and local treatment of hemorrhoids. 

It is found to possess both low potency and low systemic toxicity. It is mostly employed as a local topical anaesthetic in conjimction with other similar agents though some of these mixtures may give rise to undesired allergic manifestations. Besides, benzocaine is also employed as a possible snlphona-mide antagonist. 

It is generally employed in solution form either alone or in eombination with adrenaline (a vasodilator). It exhibits upto 95% ability to cause plasma protein binding. Beeause it exerts a minimal nerve motor block, hence it is specifically suitable for some surgieal operations. The drug is largely metabolized in the liver and its metabolites are chiefly exereted in the urine. 

Its solution finds usage as a topical local anaesthesia in dentistry. It has also been employed in several ear and nose drops for the relief of pain along with other drugs. 

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MODE OF ACTION OF SOME SELECTED LOCAL ANAESTHETICS ... 

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