Metoprolol
A cardioselective beta-1 blocker used to manage hypertension, angina, and heart failure.
Beta-1 selectivity is the detail the exam rewards. At standard doses metoprolol spares the beta-2 receptors in the lungs, so it is preferred over nonselective beta blockers (such as propranolol) for patients with asthma or COPD — but that selectivity fades at high doses, so caution still applies. Know the two salts, because they are dosed differently: immediate-release metoprolol tartrate is given twice daily for angina and after a myocardial infarction, while extended-release metoprolol succinate is given once daily and is the form used in chronic heart failure.
The most-tested teaching point is to never stop the drug abruptly — rebound tachycardia, hypertension, and even angina or MI can follow. Two classic traps round it out: metoprolol masks the tachycardia that normally warns a diabetic of hypoglycemia, and it can cause orthostatic hypotension, so patients should rise slowly. Before each dose, pair the apical-pulse check (hold for a rate below 60 bpm) with a blood-pressure parameter.
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