Lidocaine exerts its local anesthetic effect by reversibly blocking sodium channels and blocking the transmission of action potentials on nerve fibers. Sensory nerve fibers are blocked earlier than motor nerve fibers, so low doses of lidocaine can exert selective sensory blocking effects. Lidocaine also has antiarrhythmic effects and is a Class Ib antiarrhythmic drug. It can reduce ventricular rate, shorten action potential time and absolute refractory period, and prolong relative refractory period. Lidocaine has a rapid onset and a short duration. Adding epinephrine to lidocaine can reduce the rate of systemic absorption, thereby prolonging the duration of anesthesia.