Warfarin, The Bottom Line.

Warfarin is a Vitamin K antagonist. It can be reversed by administering Vitamin K but takes around 24hours as clotting factors need to be replenished.

Causes hypercoagulable state in the first 36h of use by decreasing protein C levels - NOT suitable for VTE prophylaxis for short term inpatients. Warfarin takes around 72h to take effect.

• Target INR 2.0. Start to worry when INR > 4. Consider skipping next dose and reducing the warfarin prescription.
• When INR > 9 without bleeding; Vit K 2.0mg po stat. Stop warfarin and watch until INR therapeautic. Restart on lower maintenance dose.
• Significant bleeds? Regardless of INR, start Vit K 10mg IV over 30min, then three units of fresh frozen plasma, consider 20mcg/kg Factor VIIa bolus over 5 min.