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Fenofibrate and warfarin interaction
1University of Pacific, Stockton, California, and Veterans Administration San Diego Healthcare System, USA.
Insights
Fenofibrate therapy initiation in patients on warfarin may increase bleeding risk. Close international normalized ratio (INR) monitoring is crucial to prevent supratherapeutic INR values and potential hemorrhagic events.
Area of Science:
- Pharmacology
- Clinical Medicine
Background:
- Warfarin (Coumadin) is a common anticoagulant for atrial fibrillation and coronary heart disease.
- Fenofibrate is used to manage elevated triglyceride levels.
Observation:
- A 79-year-old male patient on warfarin experienced rectal bleeding after switching from gemfibrozil to fenofibrate.
- His international normalized ratio (INR) became significantly elevated post-fenofibrate initiation.
Findings:
- Fenofibrate therapy was associated with a supratherapeutic INR in a patient stabilized on warfarin.
- No other changes in medication, diet, or lifestyle were reported by the patient.
Implications:
- Clinicians must perform serial INR monitoring when initiating fenofibrate in patients on warfarin.
- This monitoring is essential to mitigate the risk of bleeding events.
- Careful drug interaction surveillance is vital for patient safety.
Abstract:
A 79-year-old man with atrial fibrillation and coronary heart disease who was taking warfarin (Coumadin) was converted to fenofibrate from gemfibrozil therapy for persistently elevated triglyceride levels. The patient took fenofibrate for 1 month and subsequently experienced rectal bleeding that required a visit to the emergency room. Before starting fenofibrate therapy, his coagulation values were within therapeutic range, but when measured in the emergency room the international normalized ratio (INR) was grossly elevated. The patient denied any changes in diet, alcohol ingestion, compliance with therapy, or use of other new drugs except for fenofibrate. His drug therapy profile consisted of digoxin, fosinopril, and furosemide for chronic heart failure, allopurinol for gout, and potassium supplementation. To minimize the risk of supratherapeutic INR values and/or hemorrhagic events, clinicians should perform serial monitoring of INR when initiating fenofibrate therapy in a patient previously stabilized on a coumarin anticoagulant.