A 58-year-old man with a history of chronic obstructive pulmonary disease (COPD) and hypertension is being treated with a beta-blocker. All of the following beta-blockers would be relatively safe in this patient EXCEPT:

Explanation

## Beta-Blocker Selection in COPD: Cardioselectivity is Critical **Key Point:** In patients with COPD or asthma, β1-selective (cardioselective) beta-blockers are preferred because they spare β2-receptors on bronchial smooth muscle at therapeutic doses, minimizing bronchospasm risk. Non-selective agents are contraindicated. ### Comparative Safety Profile in COPD | Agent | Selectivity | β1/β2 Ratio | Safety in COPD | |-------|-------------|------------|----------------| | Atenolol | β1-selective | 1:7 | **Safe** — preferred choice | | Bisoprolol | β1-selective | 1:11.5 | **Safe** — highest selectivity | | Labetalol | Non-selective β + α1-blocker | Mixed | **Relatively safe** — weak β2 effect | | Nadolol | **Non-selective** | 1:1 | **UNSAFE** — significant β2 blockade | ### Why Nadolol is the Exception Nadolol is a **non-selective beta-blocker** with equal affinity for β1 and β2-adrenergic receptors. In COPD patients, nadolol will: 1. Block β2-receptors on bronchial smooth muscle 2. Prevent endogenous catecholamine-mediated bronchodilation 3. Precipitate or worsen bronchospasm 4. Increase airway resistance and dyspnea **Clinical Pearl:** Nadolol has a very long half-life (~20–24 hours), which means once-daily dosing is possible, but this advantage is negated by its contraindication in obstructive airway disease. **High-Yield:** Nadolol is frequently tested in "all except" questions because students may confuse its long half-life (a positive feature) with its safety profile in COPD (a negative feature). ### Why the Other Options Are Relatively Safe - **Atenolol & Bisoprolol:** β1-selective; spare β2-receptors at therapeutic doses; safe in COPD. - **Labetalol:** Although it has non-selective β-blocking activity, its β2-blocking effect is weak compared to its α1-blocking effect. The vasodilatory α1-blockade and modest β-selectivity make it relatively safer than pure non-selective agents like nadolol. **Mnemonic:** **ABCD for COPD-safe beta-blockers** = **A**tenolol, **B**isoprolol, **C**arvedilol (in heart failure despite non-selectivity), **D**on't use **N**on-selective agents like **N**adolol.