Which opioid is metabolized to normeperidine and can lead to seizures?

Meperidine, the opioid specified, is uniquely metabolized in the liver to a byproduct known as normeperidine. This metabolite can accumulate, particularly in cases of renal impairment or after prolonged use of meperidine, which has a shorter half-life than many other opioids. Normeperidine is associated with neurotoxic effects, most notably seizures. This is particularly concerning in patients who may have underlying conditions that predispose them to seizures, or those receiving higher doses or extended courses of treatment.

The other opioids listed do not share this specific metabolic pathway or associated risk. For instance, codeine is primarily converted to morphine and does not lead to the formation of normeperidine. Fentanyl is metabolized differently and is known for its rapid onset and short duration of action without the risk of seizure from a toxic metabolite. Morphine, while it has its own set of metabolites, does not produce normeperidine and is not associated with the same seizure risk that meperidine poses.

Thus, meperidine's unique metabolism to normeperidine and the resultant potential for seizure activity distinctly identify it as the correct answer.