What may an ultra-rapid CYP2D6 metaboliser experience when taking codeine?

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Multiple Choice

What may an ultra-rapid CYP2D6 metaboliser experience when taking codeine?

Codeine is a prodrug that must be activated by CYP2D6 to become morphine, the component that provides pain relief. In ultra-rapid CYP2D6 metabolizers, this activation happens more quickly and to a greater extent, so more morphine is produced than usual. That surge in morphine can lead to stronger analgesia but also a higher risk of opioid toxicity, including dangerous sedation and respiratory depression. This is why the expected outcome is increased morphine production with greater toxicity risk. The other possibilities don’t fit because analgesia would not be reduced, there wouldn’t be no change in morphine production, and while clearance might vary, the key issue with ultra-rapid metabolism is the disproportionate rise in active morphine after taking codeine.

Codeine is a prodrug that must be activated by CYP2D6 to become morphine, the component that provides pain relief. In ultra-rapid CYP2D6 metabolizers, this activation happens more quickly and to a greater extent, so more morphine is produced than usual. That surge in morphine can lead to stronger analgesia but also a higher risk of opioid toxicity, including dangerous sedation and respiratory depression. This is why the expected outcome is increased morphine production with greater toxicity risk. The other possibilities don’t fit because analgesia would not be reduced, there wouldn’t be no change in morphine production, and while clearance might vary, the key issue with ultra-rapid metabolism is the disproportionate rise in active morphine after taking codeine.

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