Question:medium
MAO inhibitors should not be used with:
MAO inhibitors should not be used with:
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Which opioid also blocks serotonin reuptake?
Updated On: Jun 24, 2026
- Pethidine
- Pentazocine
- Buprenorphine
- Morphine
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The Correct Option is A
Solution and Explanation
The danger here turns on serotonin. An MAOI keeps serotonin from being degraded, so any partner drug that pushes serotonin levels higher can tip the patient into serotonin toxicity.
Most opioids work purely on opioid receptors and leave serotonin handling alone. Pethidine is the exception: along with its analgesic action it actively blocks the reuptake of serotonin at nerve terminals. Layer that on top of an MAOI and you stack two serotonin-raising mechanisms, producing the well-described excitatory crisis (fever, rigidity, delirium, seizures) or, less often, a depressive crisis with coma and apnoea.
Morphine and buprenorphine lack this reuptake effect, so they are the preferred opioids in a patient on an MAOI. Pentazocine has only minor serotonergic activity, making it a distant second concern, which is why pethidine is graded the single best answer.
\[\boxed{\text{Pethidine}}\]
Most opioids work purely on opioid receptors and leave serotonin handling alone. Pethidine is the exception: along with its analgesic action it actively blocks the reuptake of serotonin at nerve terminals. Layer that on top of an MAOI and you stack two serotonin-raising mechanisms, producing the well-described excitatory crisis (fever, rigidity, delirium, seizures) or, less often, a depressive crisis with coma and apnoea.
Morphine and buprenorphine lack this reuptake effect, so they are the preferred opioids in a patient on an MAOI. Pentazocine has only minor serotonergic activity, making it a distant second concern, which is why pethidine is graded the single best answer.
\[\boxed{\text{Pethidine}}\]
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