This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Regional Anesthesia, Subject name: Anaesthesia
The following statements about Bupivacaine are true except: 
Select and explain. 
A. More cardio toxic than Lignocaine, B. 0.25 percent is effective for sensory block, C. Long acting drug, D. It produces methaemoglobinaemia
D: It produces methaemoglobinaemia
Answer: D: It produces methaemoglobinaemia 
Explanation: Methaemoglobinaemia is caused by prilocaine and benzocaine Prilocaine is the only local anesthetic that is metabolized to o -toluidine, which conves hemoglobin to methemoglobin producing methemoglobinemia. This is usually significant with doses of prilocaine as large as 600mg. Benzocaine used in topical local anesthetic sprays can also cause dangerous Methemoglobinemia. Treatment of medically impoant methemoglobinemia includes intravenous methylene blue (1-2 mg/kg of a 1% solution over 5 min). Methylene blue acts by reducing methemoglobin (Fe 3+ ) to hemoglobin (Fe 2+ ).