Which local anesthetic has a risk of causing methemoglobinemia?

Prilocaine is associated with a risk of causing methemoglobinemia, particularly in situations where it is used in large amounts or administered to individuals with certain predisposing factors. Methemoglobinemia is a condition where hemoglobin is oxidized to methemoglobin, which cannot effectively carry oxygen. This can lead to symptoms such as cyanosis, dizziness, and fatigue.

Prilocaine metabolizes into o-toluidine, a compound that is capable of oxidizing hemoglobin, increasing the likelihood of this adverse effect. This risk is especially notable in patients with genetic predispositions or those with compromised oxygen delivery, as well as in infants or neonates, who may be more susceptible.

In contrast, the other local anesthetics mentioned, such as bupivacaine, lidocaine, and mepivacaine, do not carry the same risk of inducing methemoglobinemia during standard clinical use, making prilocaine unique in this regard. This highlights the importance of understanding the pharmacological profiles of local anesthetics, especially in specific populations or clinical scenarios.