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Zorluk: Çok zorSubstance-Related and Addictive Disorders

A 41-year-old man is brought to the emergency department by emergency medical services due to severe agitation and abdominal cramps. The patient states he was discharged earlier this morning from a residential rehabilitation facility after completing a 5-day medically supervised withdrawal for alcohol use disorder. His past medical history is significant for a 10-year history of severe opioid use disorder, for which he has been enrolled in a methadone maintenance program for the last 3 years with no recent illicit opioid use. At the time of his discharge from the alcohol rehabilitation facility today, he was prescribed a daily oral medication to reduce alcohol cravings. He took the first dose of this new medication 45 minutes ago and rapidly developed his current symptoms. He denies consuming any alcohol since entering the rehabilitation program. His temperature is 37.8°C (100.0°F), blood pressure is 156/94 mm Hg, pulse is 112/min, and respirations are 22/min. Physical examination reveals a restless, profusely diaphoretic man. He is yawning frequently and has prominent rhinorrhea. Pupils are dilated at 7 mm bilaterally and reactive to light. Neuromuscular examination reveals diffuse myalgias but no rigidity or clonus. Bowel sounds are hyperactive. The medication prescribed at discharge most likely exerts its primary effect at which of the following targets?

  1. Mu-opioid receptorCevap
  2. B
    Aldehyde dehydrogenase
  3. C
    N-methyl-D-aspartate receptor
  4. D
    Voltage-gated sodium channel
  5. E
    Gamma-aminobutyric acid type A receptor

Cevap

The correct answer is the Mu-opioid receptor, which is the target of naltrexone.
The correct answer is the Mu-opioid receptor. This patient is experiencing precipitated opioid withdrawal, as evidenced by the classic constellation of yawning, rhinorrhea, mydriasis, diaphoresis, abdominal cramps, and hyperactive bowel sounds. He was recently prescribed a medication to reduce alcohol cravings following detoxification. Naltrexone is a first-line pharmacotherapy for alcohol use disorder that acts as a competitive antagonist at the mu-opioid receptor. Because this patient is maintained on methadone (a full mu-opioid agonist), the introduction of naltrexone rapidly displaced methadone from the opioid receptors, immediately precipitating severe withdrawal. Naltrexone is absolutely contraindicated in patients receiving opioid therapy or those with active opioid dependence.

Adım Adım Çözüm

1
Identify the clinical syndrome from the physical examination.
The patient presents with yawning, rhinorrhea, mydriasis, diaphoresis, myalgias, abdominal cramps, and hyperactive bowel sounds.
This specific constellation of symptoms is the classic toxidrome of acute opioid withdrawal.
2
Analyze the patient's medical history and current medications.
The patient is physically dependent on methadone (a full opioid agonist) and was just prescribed a new medication for alcohol craving reduction.
Determines the baseline pharmacological state and identifies the event that triggered the acute change.
3
Determine the identity and mechanism of the newly prescribed medication.
Naltrexone is a first-line treatment for alcohol cravings. Its mechanism is competitive antagonism at the mu-opioid receptor.
Naltrexone is strictly contraindicated in patients on opioid therapy because it immediately displaces opioid agonists from receptors.
4
Synthesize the findings to answer the question.
The patient was erroneously prescribed naltrexone, which targeted his mu-opioid receptors, precipitating acute withdrawal.
Directly answers the stem's inquiry regarding the primary target of the offending drug.

Anahtar Kavram

Administration of naltrexone, a mu-opioid receptor antagonist used for alcohol use disorder, is absolutely contraindicated in patients receiving opioid agonists (e.g., methadone) as it will precipitate severe, acute opioid withdrawal.
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Substance-Related and Addictive Disorders

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