Local anaesthetic causing methemoglobinuria is?: (A) Dibucaine, (B) Chlorprocaine, (C) Procaine, (D) Benzocaine
Answer is D. Ans. is 'd' i.e., Benzocaine Impoant facts about LAs Chlorprocaine is the shoest acting LA. Dibucaine is the longest acting, most potent and most toxic LA. Procaine & chlorprocaine are least potent LAs. Bupivacaine is the most cardiotoxic LA (Ropivacaine is a newer bupivacaine congener with less cardiotoxicity). Levobupivacaine (The S (-) enantiomer of bupivacaine) is less cardiotoxic and less prone to cause seizure. Prilocaine and Benzocaine can cause Methaemoglobinemia Lignocaine is the most commonly used LA. Bupivacaine has the highest local tissue irritancy. Chlorprocaine is contraindicated in spinal anaesthesia as it can cause paraplegia due to presence of neurotoxic preservative sodium metabisulphite. Procaine is the LA of choice in malignant hypehermia