A 52-year-old man with pheochromocytoma is scheduled for surgical resection. Which is the most common alpha blocker used for preoperative preparation in pheochromocytoma management?

Explanation

## Most Common Alpha Blocker for Pheochromocytoma Preoperative Preparation **Key Point:** Phenoxybenzamine is the gold-standard alpha blocker for preoperative preparation in pheochromocytoma because it is the only **irreversible, non-selective α-blocker**, providing sustained catecholamine blockade and preventing intraoperative hypertensive crisis. ### Mechanism and Clinical Rationale **High-Yield:** Phenoxybenzamine's unique properties make it ideal for pheochromocytoma: | Property | Phenoxybenzamine | Reversible α-blockers | |----------|------------------|----------------------| | **Selectivity** | Non-selective (α1, α2) | Selective or non-selective | | **Binding** | Irreversible covalent | Reversible competitive | | **Duration** | 24–48 hours (tissue-bound) | 6–12 hours | | **Catecholamine blockade** | Sustained, complete | Fluctuating | | **Intraoperative stability** | Excellent | Variable | | **Preoperative use** | Standard of care | Not recommended | ### Preoperative Protocol for Pheochromocytoma 1. **Phenoxybenzamine** 10 mg daily, titrated to 20–40 mg BD over 7–10 days - Goal: Achieve α-blockade before β-blockade - Prevents catecholamine surge during tumor manipulation 2. **Beta-blocker** (propranolol) added only AFTER α-blockade is established - Prevents reflex tachycardia and arrhythmias - Never give β-blocker first (unopposed α-stimulation → hypertensive crisis) **Clinical Pearl:** The "alpha first, then beta" rule is critical. Phenoxybenzamine's irreversible binding ensures sustained blockade even if the patient misses a dose, making it safer than reversible agents in the preoperative period. **Mnemonic:** **"PHENO for PHEO"** — **PHENOxybenzamine for PHEOchromocytoma**.