This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anesthesia, Subject name: Pharmacology
Mehemmoglobinemia is caused by 
Select and explain. 
A. Prilocarpine, B. Ropivaciane, C. Bupivacaine, D. Procaine
A: Prilocarpine
Answer: A: Prilocarpine 
Explanation: Refer Katzung 11/e p449. The admistration of large doses of prilocarpine during regional anesthesia may lead to accumulation of the metabolite o-toludine an oxidizing agent capable of conveing hemoglobin to methemoglobin