A 40-year-old woman presents with episodic severe headache, diaphoresis, and palpitations. 24-hour urine metanephrines are markedly elevated. CT abdomen shows a 3.5 cm right adrenal mass. Pre-operative alpha-blockade is planned. Which alpha-blocker is preferred and what is the recommended minimum duration before surgery?
- A Prazosin for at least 3 days
- B Doxazosin for at least 2 days
- C Phenoxybenzamine for at least 7–14 days ✓
- D Phentolamine infusion started 1 hour before incision
Correct answer: C. Phenoxybenzamine for at least 7–14 days
Explanation
Phenoxybenzamine, a long-acting non-competitive alpha-blocker, is the preferred agent for pre-operative preparation in phaeochromocytoma; at least 7–14 days are required to allow adequate volume expansion and blood pressure control. Beta-blockers are added only after adequate alpha blockade to prevent unopposed alpha stimulation. Short-acting agents like prazosin or phentolamine are not ideal for pre-operative preparation.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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