Local anesthetics cause vasodilation, which leads to rapid diffusion away from the site of action and results in a short duration of action when these drugs are administered alone. By adding the vasoconstrictor epinephrine to the local anesthetic, the rate of local anesthetic diffusion and absorption is decreased. This both minimizes systemic toxicity and increases the duration of action. Hepatic function does not affect the duration of action of local anesthesia, which is determined by redistribution and not biotransformation. Some of these local anesthetics agents confer additional benefits such as the antiarrhythmic effect of lidocaine when administered intravenously.