Which local anesthetics have the potential to form methemoglobin? (Select 3)

Benzocaine, prilocaine, and to some extent, ropivacaine, are known to have the potential to cause methemoglobinemia, although the primary concern is typically associated with benzocaine and prilocaine.

Benzocaine is an ester local anesthetic that can be metabolized into substances that oxidize hemoglobin, leading to the formation of methemoglobin. This is particularly significant with benzocaine as it is commonly used topically and in over-the-counter products.

Prilocaine, an amide local anesthetic, can also produce methemoglobin primarily through its metabolite, ortho-toluidine. This risk is particularly noted when high doses of prilocaine are used or in individuals who may have predispositions.

Ropivacaine, while an amide local anesthetic and not typically associated with methemoglobinemia, may still have a low potential, but it is not well-established compared to the primary candidates.

Mepivacaine does not have a notable association with methemoglobinemia. It is considered safer in this respect compared to the others mentioned.

Thus, the correct ones—benzocaine and prilocaine—are more directly tied to the formation of methemoglobin in clinical practice