Metoprolol vs atenolol.
This pair frustrates students because the obvious distinguishing feature, cardioselectivity, is shared. The comparison is really about evidence and pharmacokinetics rather than receptor pharmacology, which is precisely why it appears in exams.
Both are beta-1 selective, so selectivity does not separate them. What does is that metoprolol succinate has heart failure mortality evidence and atenolol does not, and that metoprolol is lipophilic and hepatically cleared while atenolol is hydrophilic and renally cleared.
Metoprolol vs Atenolol at a glance
| Property | Metoprolol | Atenolol |
|---|---|---|
| Selectivity | Beta-1 selective | Beta-1 selective |
| Lipid solubility | Lipophilic | Hydrophilic |
| Clearance | Hepatic, via CYP2D6 | Renal, largely unchanged |
| Heart failure evidence | Yes, for the succinate extended-release form | No mortality benefit demonstrated |
| CNS effects | More likely | Less likely |
| Dosing frequency | Tartrate twice daily; succinate once daily | Once daily |
Why only one is a heart failure drug
Beta blockers as a class are not interchangeable in heart failure, and only bisoprolol, carvedilol and metoprolol succinate have trial evidence of mortality benefit. Atenolol was never shown to provide it. This is an evidence distinction rather than a pharmacological one, which is why reasoning from mechanism will not get you there and the fact has to be known.
Why the salt form matters for metoprolol
Metoprolol tartrate is immediate release and dosed twice daily; metoprolol succinate is extended release and dosed once daily, and it is the succinate form that carries the heart failure evidence. Substituting one for the other on a milligram basis is a genuine prescribing error and a favourite exam detail, because the names differ by one word.
Why CYP2D6 belongs in this comparison
Metoprolol is metabolised by CYP2D6, so poor metabolisers and patients taking CYP2D6 inhibitors such as fluoxetine or paroxetine reach higher concentrations than expected. Atenolol bypasses hepatic metabolism entirely. A question that introduces an antidepressant alongside a beta blocker is usually testing this interaction.
Which one would the question pick?
Exams rarely ask what a drug does. They describe a patient and ask which of the two you would choose, so the scenarios below matter more than either drug monograph.
| Scenario | Pick | Why |
|---|---|---|
| Heart failure with reduced ejection fraction | Metoprolol succinate | One of three beta blockers with mortality evidence. |
| Significant renal impairment | Metoprolol | Hepatic clearance avoids accumulation. |
| Hepatic impairment or CYP2D6 interaction | Atenolol | Renally cleared and not metabolised. |
| Patient troubled by central side effects | Atenolol | Hydrophilic, so less CNS penetration. |
Traps that catch people on this pair
Treating metoprolol tartrate and succinate as equivalent
Only the succinate extended-release form carries the heart failure evidence, and the two are not interchangeable milligram for milligram.
Assuming cardioselective means equivalent
Both are beta-1 selective, yet only one has heart failure data. Class effects cannot be assumed in this indication.
Common questions
What is the difference between metoprolol and atenolol?
Both are beta-1 selective, so selectivity does not separate them. What does is that metoprolol succinate has heart failure mortality evidence and atenolol does not, and that metoprolol is lipophilic and hepatically cleared while atenolol is hydrophilic and renally cleared.
Is metoprolol better than atenolol?
For heart failure, yes: metoprolol succinate has mortality evidence and atenolol does not. For a patient with renal impairment, metoprolol also avoids accumulation. Atenolol is preferable where hepatic metabolism or a CYP2D6 interaction is a concern.
What is the difference between metoprolol tartrate and succinate?
Tartrate is immediate release and given twice daily; succinate is extended release and given once daily. The heart failure evidence applies to the succinate form only.
Which beta blockers are used in heart failure?
Bisoprolol, carvedilol and metoprolol succinate are the agents with demonstrated mortality benefit. Atenolol is not among them.
Go deeper on the mechanism
A comparison only sticks once the shared mechanism underneath it does, because what separates two drugs is always a variation on something they have in common.
- Beta blockers — the class both drugs belong to
- Cardiovascular pharmacology questions — test the distinction under time
- Selective versus non-selective beta blockers
Other comparisons
Heparin vs Warfarin · Warfarin vs DOACs · Unfractionated heparin vs Enoxaparin · Propranolol vs Atenolol · Amlodipine vs Nifedipine · Furosemide vs Bendroflumethiazide · Spironolactone vs Eplerenone · Simvastatin vs Atorvastatin · All comparisons
Study aid only. This page is written for learning and examination practice. It is not medical advice, not clinical decision support, and must never be used to make a decision about a real patient. Always verify against your local formulary, the product literature and a qualified pharmacist. See our medical disclaimer.
Two drugs, one property apart.
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