What effect does the addition of epinephrine to a local anesthetic have?

The addition of epinephrine to a local anesthetic primarily increases the duration of action of the anesthetic. This occurs because epinephrine is a vasoconstrictor, which means it constricts blood vessels in the area where the anesthetic is administered. By reducing blood flow to the site of injection, the clearance of the local anesthetic from that area is slowed, allowing the anesthetic to remain effective for a longer period. This prolongation of action enhances the effectiveness of the local anesthetic in clinical settings, allowing for extended pain relief during and after surgical procedures.

In addition to prolonging the anesthesia, this effect can also provide a degree of hemostasis, reducing bleeding during surgical interventions. The increased duration of action is especially beneficial in procedures that require prolonged anesthesia or pain control.