Lidocaine is a local anesthetic used in the treatment of ventricular arrhythmias that is administered intravenously. It is a class 1B antiarrhythmic drug, considered moderately effective at blocking sodium ion channels. Its chemical structure consists of an aromatic group which is linked to diethylglycine through an amine bond. Lidocaine works by slowing the rise of the action potential and is therefore effective for treating tachycardia (rapid heart rate) rather than bradycardias (slowed heart rate). The primary mechanism of action occurs in cardiomyocytes, where the unionized form of lidocaine passively diffuses through the cell membrane and into the cytosol. In the cytoplasm, lidocaine becomes ionized by hydrogen ions and is able to bind to sodium ion channels in the membrane. This locks the sodium channels in an “open” state, where they are no longer able to effectively depolarize the cell. The decreased ability to depolarize slows the generation of signals by suppressing the propagation of an action potential. In turn, the decreased action potential slows the rate of heart contractions, treating the ventricular tachycardia.

Lidocaine Mechanism of Action References