Mehemmoglobinemia is caused by
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
Prilocarpine
Ropivaciane
Bupivacaine
Procaine
Anesthesia