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NBME 22 Answers

nbme22/Block 3/Question#18

An 85-year-old woman is diagnosed with a fracture ...

Morphine is metabolized to active metabolites that accumulate

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submitted by moloko270(31),

Morphine is metabolized in the liver to morphine-6-glucuronide and morphine-3-glucuronide, both of which are excreted by the kidneys. In the setting of renal failure, these metabolites can accumulate, resulting in a lowering of the seizure threshold. Morphine should therefore be used with caution with mild renal impairment and be avoided in the setting of renal failure.

source: https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/morphine-6-glucuronide

they gave a hint of increased creatinine level, plus older age can give a slowed down metabolism and CNS symptoms

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submitted by medstudied(1),

can someone explain how morphine is degraded into active metabolites that accumulate? I couldn't find any sources that state this fact. Isn't it metabolized through the P450 system and excreted in urine?

staygoodpupper  Morphine mostly undergoes phase II metabolism and is then excreted renally. Some of the metabolites are metabolically active, and her creatinine was a little elevated, so renal clearance could have been impaired. +2