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Metoprolol Succinate vs Tartrate — EECC MCQ

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ModerateCardiac PharmacologyMetoprolol Succinate vs TartrateEECC

A 60-year-old man with stable angina on metoprolol 100 mg bd presents for review. He asks about the difference between metoprolol tartrate and metoprolol succinate for heart failure. Which formulation has evidence for mortality reduction in HF?

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Correct answer: C — Metoprolol succinate CR/XL (controlled-release extended-release) — the formulation used in the MERIT-HF trial; metoprolol tartrate (immediate-release) was not studied in HF mortality trials and should not be considered equivalent

Three beta-blockers have proven mortality benefit in HFrEF: bisoprolol (CIBIS-II), carvedilol (COPERNICUS, US Carvedilol HF), and metoprolol succinate CR/XL (MERIT-HF). Metoprolol tartrate (immediate-release) was NOT the formulation studied in these trials and has different pharmacokinetics: (1) shorter duration of action requiring more frequent dosing; (2) peak-trough fluctuations in plasma levels; (3) no mortality evidence in HF. The ESC HF Guidelines specifically recommend the CR/XL formulation (target dose 200 mg daily) for HFrEF. This distinction matters clinically — prescribing metoprolol tartrate when succinate CR/XL is intended denies the patient the evidence-based therapy. Carvedilol and bisoprolol do not have this formulation issue.

Reference: ESC (2023): HF Guidelines; MERIT-HF Trial