NAPLEX (North American Pharmacist Licensure Examination) Practice Exam

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Prepare to ace the NAPLEX. Utilize flashcards and multiple choice questions with hints and explanations. Equip yourself thoroughly for the exam!

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

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Which opioid's metabolite can accumulate and cause CNS toxicity, including seizures?

  1. Morphine

  2. Meperidine

  3. Methadone

  4. Fentanyl

The correct answer is: Meperidine

Meperidine is the correct answer because its metabolite, normeperidine, can accumulate in the body and cause CNS toxicity, including seizures. Normeperidine is formed when meperidine is metabolized by the liver. Unlike other opioids, meperidine has an active metabolite that can build up in the body, especially in patients with renal impairment or those receiving high doses or prolonged therapy. This accumulation can lead to adverse effects, such as seizures, especially in vulnerable populations. Morphine, methadone, and fentanyl do not have metabolites that accumulate to the same extent as normeperidine, making them less likely to cause CNS toxicity and seizures through metabolite accumulation.