Question
Cardioselective beta blockers
Answer
Cardioselective (beta-1-selective) blockers preferentially block beta-1 receptors over beta-2 at usual therapeutic doses, sparing bronchial and vascular beta-2 receptors.
Examples: Atenolol, Metoprolol, Bisoprolol, Esmolol (ultra-short-acting, IV).
Advantage over non-selective agents: reduced risk of bronchospasm — safer (though still used cautiously) in patients with mild reactive airway disease, and less interference with beta-2-mediated peripheral vasodilation and hypoglycemia counter-regulation in diabetics. Selectivity is relative and lost at higher doses.
Uses: hypertension, angina, post-MI, arrhythmias, heart failure (bisoprolol, metoprolol succinate — specifically studied for mortality benefit).
Adverse effects: bradycardia, fatigue, cold extremities, still some risk of bronchospasm at higher doses, masking of hypoglycemia symptoms.