Metoprolol
Beta Blocker, Cardioselective (β1)
Metoprolol
Lopressor (tartrate), Toprol XL (succinate)
Metoprolol is a cardioselective (β1-preferring) beta blocker that comes in two salt forms: tartrate (short-acting, BID dosing) and succinate (extended-release, once-daily, and the only form approved for heart failure with reduced ejection fraction). Cardioselectivity makes it a reasonable first-line option in patients with mild reactive airway disease, though β2 effects emerge at higher doses.
Heart rate, blood pressure; in HFrEF, watch for fluid retention during titration.
Do not stop abruptly. Tartrate and succinate are NOT interchangeable mg-for-mg, succinate is once-daily and the only form proven in HF trials.
Propranolol, Bisoprolol, Nebivolol
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Pharmacokinetics
Absorption
~50% oral bioavailability.Distribution
Modest plasma protein binding (~12%). Some CNS penetration but less than propranolol.Metabolism
Hepatic via CYP2D6. Poor metabolizers have higher exposure and more pronounced effect.Elimination
Renal excretion of metabolites.Interactions
Pharmacogenomic + mechanism interactions
Pharmacogenomic guideline recommendationsCPIC and Dutch Pharmacogenetics Working Group clinical guidelines
CPIC rec 8094566 [Strong]: Initiate standard dosing CPIC pair-level B (CYP2D6, ADRB1, ADRB2, ADRA2C, GRK4, and GRK5 and Beta-Blockers) [PMID 38951961]
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CPIC rec 8094578 [Moderate]: Initiate therapy with lowest recommended starting dose. Carefully titrate dose upward to clinical effect or guideline-recommended dose; monitor more closely for bradycardia. Alternatively, consider selecting another beta-blocker. CPIC pair-level B (CYP2D6, ADRB1, ADRB2, ADRA2C, GRK4, and GRK5 and Beta-Blockers) [PMID 38951961]
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CPIC rec 8094574 [Moderate]: Initiate standard dosing CPIC pair-level B (CYP2D6, ADRB1, ADRB2, ADRA2C, GRK4, and GRK5 and Beta-Blockers) [PMID 38951961]
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CPIC rec 8094565 [No Recommendation]: No recommendation for metoprolol therapy due to insufficient evidence regarding diminished metoprolol effectiveness clinically CPIC pair-level B (CYP2D6, ADRB1, ADRB2, ADRA2C, GRK4, and GRK5 and Beta-Blockers) [PMID 38951961]
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Clinical relevance: does this interaction matter in practice?trivialcritical
Mechanism description, if it needs work:
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Experience (1 a little, 5 a lot)
Outcome (-100 worst, +100 best)
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See also
References
Summary
Classes
Beta Blocker, Cardioselective (β1)
Common uses
Hypertension0, Angina0, Post-MI cardioprotection0, Heart failure (succinate only)0, SVT0
Pharmacy
Starting dose
25–50 mg BID (tartrate); 25–100 mg daily (succinate); 12.5 mg daily in HFrEF
Preparations
Tartrate: 25, 50, 100 mg tabs; 1 mg/mL IV. Succinate ER: 25, 50, 100, 200 mg.
US FDA Max
400 mg/d
Pharmacology
Routes
Oral, IV
Onset
1–2 h (PO); immediate (IV)
Duration
6–12 h (tartrate); 24 h (succinate)
Half-life
3–7 h
Bioavailability
~50%
Pregnancy
Category C
Legal status
Rx-only in US
Purported mechanism
Cardioselective β1-adrenergic antagonist. Selectivity is dose-dependent and partially lost at higher doses.