Metoprolol is a cardioselective beta-1 adrenergic receptor blocker that has been widely used in cardiovascular medicine for decades. It works by competitively blocking beta-1 receptors in the heart, reducing heart rate, contractility, and cardiac output, and lowering myocardial oxygen demand. This action makes it especially useful for treating conditions where reducing cardiac workload is beneficial, such as hypertension, angina, and post-myocardial infarction secondary prevention. Unlike non-selective beta-blockers (e.g., propranolol), metoprolol has relatively little effect on beta-2 receptors in the lungs and vasculature at lower doses, though this selectivity diminishes at higher doses.
Two major salt forms exist: metoprolol tartrate, which has a shorter half-life (requiring multiple daily doses), and metoprolol succinate, an extended-release formulation that allows for once-daily dosing. Both forms have the same pharmacological activity but differ in clinical convenience and compliance. Metoprolol is extensively metabolised in the liver by CYP2D6, leading to variability in plasma levels depending on genetic polymorphisms, drug interactions, and hepatic function.
Large clinical trials, including MERIT-HF and others, have established its benefit in chronic heart failure with reduced ejection fraction (HFrEF), where it lowers mortality and reduces hospitalisation. In hypertension, metoprolol effectively lowers blood pressure, though current guidelines often recommend it as a second-line or add-on therapy unless there is a specific compelling indication (e.g., angina, arrhythmia, heart failure, or post-MI). Its role has shifted from universal first-line antihypertensive to targeted use in cardiovascular risk management, but it remains a cornerstone drug in many patient populations.
Metoprolol is generally well tolerated, but potential adverse effects include bradycardia, fatigue, cold extremities, and masking of hypoglycaemia symptoms in diabetics. Awareness of these risks and appropriate monitoring are essential. Because it is lipophilic, metoprolol crosses the blood-brain barrier and may cause central nervous system effects such as vivid dreams or sleep disturbance in some patients. Its balance of efficacy, tolerability, and cost keeps it among the most prescribed beta-blockers worldwide.
Metoprolol has multiple well-established indications across cardiovascular medicine:
Metoprolol tartrate: usually 50–100 mg twice daily, titrated to effect. Metoprolol succinate (extended release): 25–200 mg once daily, titrated based on indication (e.g., start 12.5–25 mg in HFrEF and slowly up-titrate every 2–4 weeks).
Therapy must be individualised. Abrupt withdrawal can precipitate angina, arrhythmia, or even myocardial infarction; taper gradually when discontinuing. Lifestyle measures (diet, exercise, smoking cessation, adherence to other cardiovascular therapies) are key complements.
Most side effects are dose dependent and improve with dose adjustment or switching to another beta-blocker. Patients should report persistent fatigue, worsening shortness of breath, or fainting spells promptly.
Monitor blood pressure, heart rate, and symptoms regularly, especially during initiation or dose titration. Provide patients with clear sick-day and withdrawal guidance.
Patients should maintain an updated medication list and review it with their healthcare provider when new drugs are prescribed.
Overdose: Symptoms include profound bradycardia, hypotension, AV block, cardiogenic shock, and possible cardiac arrest. CNS effects (confusion, seizures) may occur. Management includes IV fluids, atropine for bradycardia, glucagon infusion (bypasses beta-receptor blockade), high-dose insulin therapy for cardiogenic shock, and vasopressors. Severe cases may require temporary pacing or mechanical support.
Accidental double dose: May cause dizziness, slow pulse, or fainting. Monitor closely; seek medical advice if symptomatic. Do not self-administer further doses until reviewed.
Missed dose: Take it as soon as remembered unless near the time of the next dose. Never double up. For extended-release, if >12 hours late, skip and resume next scheduled dose.
Check expiration date before use. Carry a current prescription label when travelling, and store medication in hand luggage rather than checked baggage to avoid extremes of temperature.
The information provided on this website is for general educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor, pharmacist, or other qualified health provider with any questions you may have regarding a medical condition or medication. Do not disregard professional medical advice or delay seeking it because of something you have read here. We do not take responsibility for any loss, damage, or injury caused by this information.