What is the primary metabolite of prilocaine that can lead to methemoglobinemia?

The primary metabolite of prilocaine that can lead to methemoglobinemia is norprilocaine. When prilocaine is metabolized, it is converted into various metabolites, with norprilocaine being one that is specifically significant due to its potential effects on hemoglobin.

Norprilocaine itself can oxidize hemoglobin to form methemoglobin, which is unable to carry oxygen effectively. This condition, methemoglobinemia, can lead to symptoms such as cyanosis and fatigue, as the body's tissues may not receive adequate oxygen. The tendency for methemoglobinemia is more pronounced with prilocaine compared to some other local anesthetics, making it important for practitioners to be aware of its metabolite when using this drug.

The other metabolites mentioned, such as para-aminobenzoic acid, hippuric acid, and phenylacetic acid, do not directly contribute to the formation of methemoglobin and thus do not carry the same risk in this context.