CRDTS Local Anesthesia Practice Test

Long duration of action with amide local anesthetics comes from higher lipid solubility and greater protein binding, which keeps the drug in the nerve tissue longer and slows its clearance. Among these options, bupivacaine has the highest lipid solubility and protein binding, so its effects persist longer than lidocaine, mepivacaine, or prilocaine—especially when a vasoconstrictor is used to reduce systemic uptake. That combination yields the longest-lasting anesthesia in typical practice. The other agents are less lipid-soluble and less protein-bound, so their effects wear off sooner. Remember, the longer duration also means a higher potential for toxicity, so dosing and monitoring are important.