Key result
Amiodarone reduced total plasma warfarin clearance in patients, without changing the binding of warfarin to plasma proteins.
Why the study?
Does amiodarone reduce plasma warfarin clearance in patients?
Observational (n=8)
Does amiodarone reduce plasma warfarin clearance in patients?
Amiodarone potentiates the action of warfarin by reducing its total plasma clearance, explaining a well-known drug interaction.
May warrant closer INR monitoring with amiodarone-warfarin coadministration; hypothesis-generating from Level 5 evidence and requires prospective validation.
Amiodarone is an effective antiarrhythmic agent whose use is associated with several drug interactions one of which is potentiation of the action of warfarin. The mechanism of this interaction has hitherto been unclear. We examined possible mechanisms in eight patients. Total plasma warfarin clearance was found to be reduced by amiodarone. No change was detected in the binding of warfarin to plasma proteins. No relationship was found between plasma amiodarone concentrations and the change in warfarin clearance.
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Watt et al. (1985) conducted an observational in Patients taking warfarin and amiodarone (n=8). Amiodarone was evaluated on Total plasma warfarin clearance. Amiodarone reduced total plasma warfarin clearance in patients, without changing the binding of warfarin to plasma proteins.