Which local anaesthetic has the HIGHEST cardiotoxic to neurotoxic ratio, making its inadvertent intravascular injection particularly dangerous?

• A Lidocaine
• B Ropivacaine
• C Prilocaine
• D Bupivacaine ✓

Explanation

Bupivacaine has a narrow ratio between the convulsant dose (CNS toxicity) and the cardiotoxic dose compared with lidocaine. Its high lipid solubility and protein binding cause it to bind tightly to cardiac sodium channels in a 'fast-in, slow-out' kinetic pattern, making resuscitation from bupivacaine cardiac arrest extremely difficult. Ropivacaine was developed as a safer alternative with similar potency but less cardiotoxicity due to its S-enantiomer formulation. Lidocaine and prilocaine have a wider safety margin between CNS and cardiac toxicity thresholds.

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.