A patient maintained on methadone 80 mg daily is given buprenorphine too soon after his last methadone dose and abruptly develops features of acute opioid withdrawal. The pharmacodynamic explanation for this precipitation is:

• A Buprenorphine is a full mu receptor agonist that overshoots receptor activation
• B Buprenorphine accelerates methadone clearance by inducing CYP2B6
• C Buprenorphine blocks kappa receptors, unmasking dysphoria interpreted as withdrawal
• D Buprenorphine has higher mu receptor affinity but lower intrinsic activity, displacing methadone and reducing net receptor activation ✓

Explanation

Buprenorphine binds the mu receptor with very high affinity but has low intrinsic activity, making it a partial agonist. When given before methadone levels fall, it competitively displaces methadone from mu receptors and provides less receptor activation, dropping the patient below their physical dependence threshold and precipitating withdrawal. Option A contradicts its partial agonist nature, and pharmacokinetic acceleration plays no role here.

Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.

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Written and medically reviewed by the StethoPrep medical team.