Lidocaine receptor site

A growing number of other diverse compounds have also been shown to bind to an allosteric site on the muscarinic receptors. Among them are pirenzepine (highly selective for Mi receptor), lidocaine and verapamil (ion channel blockers), tacrine (anticholinesterase compound), batrachotoxin, and strychnine (glycine receptor antagonist) [25,31-35],... 

Amide-type local anesthetics (e.g., procainamide and lidocaine) also possess antiarrhythmic activity when given parenterally and at a subanesthetic dosage. Although this action can be attributed to their actions on sodium channels in cardiac tissues, current evidence suggests a distinctly different mechanism of action with respect to the modulation of channel receptors and the location of binding sites for these compounds (19,20). 

Its duration of action is 60-120 minutes, depending on the vascularity of the site blocked as well as added adjuvants such as epinephrine. The drug is 70% protein-bound, with 30% in the free unbound form. It is this 30% that is rapidly cleared by the systemic circulation for hepatic metabolism. The vasoconstrictive properties of epinephrine help to decrease this systemic uptake of the drug and thus to prolong its duration of action. Other adjuvants such as the alpha-2 receptor agonists clonidine and dexmedetomidine have been studied recently and found to prolong the duration of action of lidocaine. Their mechanism of action (specific receptor vs. pharmacokinetic/phar-macodynamic interaction with local anesthetics) and site (central vs. peripheral) of action have not been fully elucidated [6-8]. 

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