What is the duration of action for bupivacaine?

• A. Very short duration (minutes)
• B. Moderate duration (30-60 minutes)
• C. Long duration (2-4 hours)
• D. Extremely long duration (6-8 hours)

Answer: (C)

Local anesthetics vary in how long they keep the nerve blocked. Bupivacaine is a long-acting amide, so it stays at the nerve site longer than many other agents. Its high lipid solubility and strong protein binding mean it penetrates and remains near the sodium channels for an extended period, producing a longer duration of anesthesia. Adding a vasoconstrictor like epinephrine further prolongs effect by reducing blood flow and slowing systemic absorption. In typical office settings, this combination yields a duration around two to four hours, longer than agents like lidocaine or mepivacaine but shorter than some ultra-long options.