## Clinical Context This patient developed bronchospasm due to propranolol, a **non-selective beta blocker** that blocks both β₁ (cardiac) and β₂ (bronchial) receptors. The β₂ blockade causes bronchoconstriction in susceptible patients. ## Why Bisoprolol Is Correct **Key Point:** Bisoprolol is a **cardioselective (β₁-selective) beta blocker** with the highest β₁/β₂ selectivity ratio among available agents. **High-Yield:** Cardioselective beta blockers (atenolol, metoprolol, bisoprolol, nebivolol) preferentially block β₁ receptors at therapeutic doses, sparing β₂-mediated bronchodilation. Bisoprolol has the **best selectivity profile** (up to 200-fold), making it safest in patients with reactive airway disease. **Clinical Pearl:** Even cardioselective agents lose selectivity at high doses, but bisoprolol maintains selectivity across the entire therapeutic range, making it ideal for this patient. ## Comparison of Beta Blockers in Bronchospasm Risk | Beta Blocker | Selectivity | Bronchospasm Risk | Suitable for COPD/Asthma? | |---|---|---|---| | Propranolol | Non-selective | Very high | No | | Atenolol | β₁-selective | Low–moderate | Relatively safe | | Bisoprolol | β₁-selective (highest) | Lowest | **Best choice** | | Labetalol | Mixed (α + β) | Moderate | Not ideal | | Sotalol | Non-selective | Very high | No | ## Why Bisoprolol Over Atenolol? While atenolol is also cardioselective, bisoprolol has: - Superior β₁/β₂ selectivity ratio - Longer half-life (10–12 hours vs. 6–7 hours) - Better tissue penetration and efficacy - Lipophilic properties allowing CNS effects (may reduce anxiety in some patients) **Tip:** In NEET PG exams, when a patient with asthma/COPD needs a beta blocker, **bisoprolol** is the preferred answer due to its unmatched selectivity. Atenolol is second choice. [cite:KD Tripathi 8e Ch 12]
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