Metoprolol
- Class: Beta-1 blocker
- Used for: a racing heart
- Say it: meh-TOH-proh-lol
- Forms: tablet, injection
METOPROLOL = a METRONOME, slowed down. The racing heart is set back to a steady, unhurried beat.
Blocking beta-1 receptors on the heart slows both rate and force — the metronome really is turned down.
One heart, two lungs. Metoprolol is beta-1 selective, so it slows the heart while largely sparing the beta-2 receptors that keep airways open.
Side effects
Common: fatigue, slow heart rate, cold hands
Serious: heart block, rebound if stopped suddenly
Typical dose
Tartrate 25–100 mg twice daily; succinate 25–200 mg once daily
The two salts are not interchangeable. Succinate is the once-daily form with the heart failure evidence.
Check yourself
Why is Metoprolol preferred over propranolol in someone with asthma?
- It is beta-1 selective, so it mostly spares the beta-2 receptors that keep airways open
- It blocks beta-2 receptors more strongly
- It is a calcium channel blocker, not a beta blocker
- It is not absorbed well enough to reach the lungs
Show answer
A. It is beta-1 selective, so it mostly spares the beta-2 receptors that keep airways open
Selectivity is the whole point: beta-1 sits mainly on the heart, beta-2 on airway muscle. Propranolol blocks both, which can tighten the airways. Selectivity is relative, though — it fades at higher doses.
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