คำอธิบาย
Trimethoprim (alone or in combination as TMP-SMX) increases warfarin's anticoagulant effect through CYP2C9 inhibition, raising INR and bleeding risk.
กลไก
Trimethoprim inhibits CYP2C9, reducing the metabolism of S-warfarin; the sulfonamide component of TMP-SMX also displaces warfarin from plasma proteins.
ความสำคัญทางคลินิก
INR elevations averaging 50–100% have been documented; bleeding complications including epistaxis, bruising, and GI hemorrhage have been reported.
การจัดการ
Monitor INR within 3–5 days of starting TMP or TMP-SMX; consider reducing warfarin dose by ~10–25% preemptively in high-risk patients.
ข้อจำกัดความรับผิดชอบทางการแพทย์
This content is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making medication decisions.