Which substance is known to convert hemoglobin to methemoglobin?

Prilocaine is known to convert hemoglobin to methemoglobin due to its metabolic byproducts. When prilocaine is administered, it can be metabolized to ortho-toluidine, which has the ability to oxidize iron in hemoglobin from the ferrous (Fe2+) to the ferric (Fe3+) state. This conversion results in methemoglobin, which is incapable of effectively transporting oxygen throughout the body.

Methemoglobinemia, a condition characterized by an elevated level of methemoglobin, can be a side effect of prilocaine use, particularly when used in large doses or in certain patients. This is important for healthcare providers to consider to avoid potential complications related to oxygen transport in patients receiving this anesthetic.

While substances like benzocaine and mepivacaine are also used as local anesthetics, they do not have the same chemical action as prilocaine that leads to the formation of methemoglobin. EMLA cream, which is a combination of lidocaine and prilocaine, also poses a similar risk as prilocaine given its content. However, it is the prilocaine component that is primarily responsible for converting hemoglobin to methemoglobin.