Warfarin: Key Facts and Mnemonics

Introduction

• Warfarin is a common anticoagulant used to prevent blood clots.
• Mnemonic: War to remember warfarin.

How Warfarin Works

• Acts as a blood thinner to prevent the formation of blood clots.
• Clinical Uses:
  • Prevent clots in patients with DVTs (Deep Vein Thrombosis), pulmonary embolisms, heart attacks, strokes, etc.

Side Effects

• Major side effect: Bleeding (e.g., severe bruising, tarry stools, sudden drop in blood pressure).
  • Symbol: Warrior with bleeding arm.

Monitoring Lab Values

• PT (Prothrombin Time):
  • Measures the time it takes for blood to clot.
  • Target: 2-3 times the patient’s baseline.
  • Symbol: Paper towel (PT = paper towels).
• INR (International Normalized Ratio):
  • Derived from PT, normalizing the patient's PT by the international average.
  • Target INR: Between 2 and 3.
  • Symbol: Eyeliner (INR = I-LINE-ER).
  • INR of 2: Blood takes twice as long to clot.
  • INR of 3: Blood takes thrice as long to clot.

Contraindications

• Teratogenic Effects:
  • Warfarin is teratogenic, causing birth defects.
  • Contraindicated in pregnancy.
  • Symbol: Tarantula (teratogenic tarantula).

Dietary Considerations

• Vitamin K:
  • Leafy greens (like kale) are high in Vitamin K and can reverse warfarin’s effects.
  • Patients should avoid excess intake of leafy greens.
  • In case of warfarin overdose or before surgery, Vitamin K can be administered via injection or IV to reverse effects.
  • Symbol: Kale (vitamin K).

Summary

• Uses: Prevention of DVTs, pulmonary embolisms, heart attacks, strokes.
• Side Effect: Increased risk for uncontrolled bleeding.
• Monitoring: PT and INR levels (therapeutic INR: 2-3).
• Contraindications: Teratogenic, avoid in pregnancy.
• Diet: Avoid excess leafy greens (high in Vitamin K).
• Reversal: Vitamin K via injection or IV reverses warfarin’s effects.

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