Which local anesthetic is the long-acting one?

Which local anesthetic is the long-acting one?

• A. Bupivacaine
• B. Lidocaine
• C. Prilocaine
• D. Mepivacaine

Answer: (A)

The length of how long a local anesthetic lasts depends on how soluble it is in fats and how strongly it binds to proteins in tissues. The more lipid-soluble and protein-bound, the longer it stays near the nerve and keeps the block going. Among these common amide anesthetics, bupivacaine is the most lipid-soluble and has strong protein binding, so it produces the longest-lasting nerve block. That’s why it’s the best answer for “the long-acting one.” If you add epinephrine, its duration is extended even further by reducing systemic absorption. By contrast, lidocaine tends to act more quickly but wears off sooner, while prilocaine and mepivacaine have intermediate durations.

The length of how long a local anesthetic lasts depends on how soluble it is in fats and how strongly it binds to proteins in tissues. The more lipid-soluble and protein-bound, the longer it stays near the nerve and keeps the block going. Among these common amide anesthetics, bupivacaine is the most lipid-soluble and has strong protein binding, so it produces the longest-lasting nerve block. That’s why it’s the best answer for “the long-acting one.” If you add epinephrine, its duration is extended even further by reducing systemic absorption. By contrast, lidocaine tends to act more quickly but wears off sooner, while prilocaine and mepivacaine have intermediate durations.