Key result
Amiodarone combined with metoprolol is linked to higher metoprolol plasma levels and lower heart rate.
Why the study?
Amiodarone weakly inhibits CYP2D6, potentially increasing metoprolol concentrations and risks of bradycardia and atrioventricular block, but whether random plasma concentrations can identify this interaction was unconfirmed.
Does concomitant amiodarone use increase metoprolol plasma concentrations and lower heart rate in adults taking metoprolol?
Cross-Sectional (n=999)
Does concomitant amiodarone use increase metoprolol plasma concentrations and lower heart rate in adults taking metoprolol?
p-value: p=0.0132
Concomitant use of amiodarone and metoprolol is associated with significantly higher metoprolol plasma concentrations and lower heart rates, demonstrating a clinically relevant pharmacokinetic interaction detectable via random blood sampling.
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May warrant heart rate monitoring with combined use; leaves open whether prospective trials should guide dose adjustments.
Robert et al. (2023) conducted a cross-sectional in Patients taking metoprolol (n=999). Amiodarone vs. Metoprolol alone (no amiodarone) was evaluated on Metoprolol plasma concentrations (p=0.0132). Amiodarone use in patients taking metoprolol was significantly associated with higher metoprolol plasma concentrations (p=0.0132) and lower heart rate (p=0.0001).
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