Which is the least toxic local anesthetic that also carries the risk of methemoglobinemia?

Which is the least toxic local anesthetic that also carries the risk of methemoglobinemia?

• A. Prilocaine
• B. Lidocaine
• C. Mepivacaine
• D. Bupivacaine

Answer: (A)

Prilocaine is the safest in terms of overall systemic toxicity to the heart and brain among these common local anesthetics, so it tends to have the lowest risk of LAST (local anesthetic systemic toxicity) compared with others like bupivacaine, mepivacaine, or lidocaine. However, its metabolism produces o-toluidine, a metabolite that can oxidize hemoglobin to methemoglobin. That means prilocaine has a real risk of causing methemoglobinemia, especially at higher doses or in susceptible patients. So, while it’s the least toxic option overall, it still carries that methemoglobinemia risk, distinguishing it from the others listed.

Prilocaine is the safest in terms of overall systemic toxicity to the heart and brain among these common local anesthetics, so it tends to have the lowest risk of LAST (local anesthetic systemic toxicity) compared with others like bupivacaine, mepivacaine, or lidocaine. However, its metabolism produces o-toluidine, a metabolite that can oxidize hemoglobin to methemoglobin. That means prilocaine has a real risk of causing methemoglobinemia, especially at higher doses or in susceptible patients. So, while it’s the least toxic option overall, it still carries that methemoglobinemia risk, distinguishing it from the others listed.