A 48-year-old man abruptly stops clonidine, which he had been taking for years. Two days later he presents with headache, palpitations, sweating, and a blood pressure of 210/120 mmHg. The mechanism of this phenomenon and the appropriate management are:
- A Depletion of catecholamine stores; give tyramine-rich fluids
- B Supersensitivity of alpha-2 receptors; restart clonidine and taper slowly, with labetalol if needed ✓
- C Renin surge from volume contraction; give furosemide alone
- D Autoimmune adrenalitis; give hydrocortisone
Correct answer: B. Supersensitivity of alpha-2 receptors; restart clonidine and taper slowly, with labetalol if needed
Explanation
Abrupt withdrawal of a central alpha-2 agonist causes rebound hypertensive crisis driven by upregulated presynaptic alpha-2 receptors and unopposed norepinephrine release. Standard management is to reinstate clonidine and taper gradually; intravenous labetalol or nitroprusside can be used if urgent control is required. Catecholamine depletion is the mechanism of reserpine action and would lower, not raise, blood pressure. Volume contraction from diuresis worsens the picture, and adrenal pathology plays no role here.
Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.
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