Which local anesthetic is known to cause methemoglobinemia?

The local anesthetic that is known to cause methemoglobinemia is Prilocaine. Methemoglobinemia is a condition where a higher than normal level of methemoglobin, a form of hemoglobin that is unable to carry oxygen, is present in the blood. Prilocaine has been associated with this side effect, particularly in higher doses or in susceptible patients.

This side effect occurs because Prilocaine can be metabolized to o-toluidine, which induces the conversion of hemoglobin to methemoglobin. While other local anesthetics may have their side effects, they do not typically cause methemoglobinemia to the same extent as Prilocaine. Understanding this particular adverse effect is important for clinicians when selecting a local anesthetic, especially in patients who may be vulnerable due to pre-existing conditions or concurrent medications that could exacerbate this reaction.