Cardioselective agents spare beta-2 receptors; non-selective agents do not
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Cardioselective (beta-1): atenolol, bisoprolol, metoprolol, nebivolol
- Relatively spare bronchial and vascular beta-2 receptors
- Preferred in asthma and COPD, though selectivity is only relative and dose dependent
- Bisoprolol is the standard choice in heart failure
Non-selective: propranolol, sotalol, nadolol, timolol
- Propranolol: lipid soluble, crosses the blood-brain barrier, used in migraine prophylaxis, essential tremor, anxiety and thyrotoxicosis
- Sotalol: also a class III antiarrhythmic, prolonging the QT interval
Mixed alpha and beta: carvedilol, labetalol (the latter used in pregnancy and in hypertensive emergency)
Adverse effects: fatigue, cold extremities, bradycardia, bronchospasm, erectile dysfunction, vivid dreams, and masking of hypoglycaemic warning symptoms in diabetes, leaving sweating as the only clue.
Never stop abruptly in ischaemic heart disease, since receptor upregulation causes rebound tachycardia, hypertension and angina.
In heart failure, beta blockers improve survival but must be started at low dose and titrated slowly when the patient is euvolaemic, since the initial negative inotropic effect can worsen symptoms.