lidokaiin

Lidocaine, also known as lignocaine, is a widely used amide-type local anesthetic and a class Ib antiarrhythmic agent. It is used to numb tissue for minor procedures, to block nerves in regional anesthesia, and in topical forms such as creams, gels, and patches. It is also employed intravenously for certain ventricular arrhythmias.

Mechanism of action: Lidocaine blocks voltage-gated sodium channels in nerve membranes, preventing the initiation and propagation of action potentials. This action underlies its anesthetic effect. At higher concentrations, it can stabilize cardiac membranes and suppress abnormal automaticity, which accounts for its antiarrhythmic use. Co-administration with vasoconstrictors (e.g., epinephrine) can slow local blood flow and extend duration of effect.

Pharmacokinetics: After administration, lidocaine is rapidly absorbed and acts quickly, with onset within minutes. Duration depends on dose, route, and presence of vasoconstrictors. It is primarily metabolized in the liver by cytochrome P450 enzymes to active metabolites such as monoethylglycinexylidide (MEGX) and glycinexylidide (GX); these are further processed and excreted in urine.

Safety and potential adverse effects: Common adverse effects include ring of numbness, tongue tingling, lightheadedness, and, at higher plasma levels, seizures or coma. Cardiovascular toxicity may include bradycardia and hypotension. Local or systemic hypersensitivity is uncommon but possible. Contraindications include hypersensitivity to amide-type local anesthetics, significant hepatic impairment, and certain conduction abnormalities; caution is advised during pregnancy and in pediatric patients. Drug interactions can occur with other sodium channel blockers and CNS or cardiovascular depressants.

History and status: Lidocaine is a standard medication with multiple formulations and is listed among essential medicines in many health systems.