CRDTS Local Anesthesia Practice Test

The duration of anesthesia from a local anesthetic is mainly governed by how readily the drug remains in the nerve and how tightly it binds to nerve proteins. Bupivacaine is highly lipid-soluble and has strong protein binding, so it diffuses into nerve tissue and stays there longer, producing a longer-lasting blockade. This extended nerve effect translates into more prolonged postoperative analgesia compared with other common anesthetics. When used with a vasoconstrictor like epinephrine, its duration is further extended because blood flow is reduced, slowing the drug’s removal from the site. The other agents—lidocaine, articaine, and prilocaine—tend to have shorter durations due to less lipid solubility and protein binding, so they provide quicker onset but briefer postoperative pain relief.