Among the local anesthetics listed, Bupivacaine provides the longest duration of anesthesia.

- Local anesthetics differ in their onset, potency, and duration of action.
- The duration of anesthesia depends primarily on the drug's lipid solubility, protein binding capacity, and vasodilatory effects.

- Lidocaine is a commonly used amide local anesthetic with a moderate duration of action (approximately 1–2 hours).
- Mepivacaine has a similar duration to lidocaine but is known for causing minimal vasodilation, which can slightly prolong its anesthetic effect.
- Prilocaine has a duration similar to lidocaine but is less potent and less vasodilatory.
- Bupivacaine is highly lipid-soluble and has a high protein-binding capacity, resulting in a significantly longer duration of anesthesia (3–10 hours), often used for procedures requiring prolonged pain relief.

Because of these pharmacokinetic properties, Bupivacaine is the local anesthetic of choice when longer duration of anesthesia is needed.

Key Points:
- Bupivacaine — longest duration due to high lipid solubility and protein binding.
- Lidocaine, Mepivacaine, and Prilocaine — shorter duration, more suitable for procedures requiring shorter anesthesia.

Reference: Goodman & Gilman's The Pharmacological Basis of Therapeutics, 13th Edition, Chapter on Local Anesthetics/Page 538–542