Lecture Notes: Anticoagulants - Heparin and Warfarin

Introduction

• Focus: Heparin and Warfarin
• Context: Cardiovascular section in pharmacology
• Purpose of anticoagulants:
  • Prevent new clots from forming
  • Prevent existing clots from growing larger
• Misconception: Anticoagulants do not thin the blood or dissolve clots

Therapeutic Uses

• Prevention and treatment of blood clots
• Conditions:
  • Deep Vein Thrombosis (DVT)
  • Pulmonary Embolisms (PE)
  • Atrial Fibrillation (AFib)
• Post-operative clot prevention

Medication Names

• Warfarin: Brand name Coumadin
• Heparin:
  • Available as Heparin Sodium
  • Low Molecular Weight Heparin (LMWH)
    • Example: Enoxaparin (Brand name Lovenox)
    • Recognizable by suffix "-parin"

Differences Between Heparin and LMWH

• LMWH:
  • More stable response
  • Lower risk of bleeding

Key Differences Between Heparin and Warfarin

• Administration:

  • Heparin: IV or subcutaneous (not orally due to gastric acid inactivation)
  • Warfarin: Orally or IV (commonly orally)

• Onset:

  • Heparin: Rapid (minutes)
  • Warfarin: Slow (hours to days)

• Combination Therapy:

  • Possible to give both until warfarin reaches therapeutic levels

Pregnancy Considerations

• Heparin: Safe (does not cross placenta or breast milk)
• Warfarin: Unsafe (crosses placenta, teratogenic)

Monitoring

• Heparin:

  • Measured with aPTT (Activated Partial Thromboplastin Time)
  • Normal range: 47-70 seconds

• Warfarin:

  • Measured with INR (International Normalized Ratio)
  • Normal range: 2-3

• Out of Range Effects:

  • High values: Increased bleeding risk
  • Low values: Clots may grow

Antidotes

• Heparin: Protamine sulfate
• Warfarin: Vitamin K

Patient Education

• Warfarin:

  • Consistent Vitamin K intake (foods like leafy greens, liver)

• Heparin:

  • Subcutaneous injection in abdomen (2 inches from umbilicus, 90-degree angle)
  • Possible bruising and irritation post-injection

• Bleeding Precautions:

  • Avoid NSAIDs, aspirin, certain antibiotics, alcohol
  • Use soft-bristled toothbrush, electric razor
  • Remove throw rugs, avoid contact sports

Review Summary

• Administration: Heparin (IV/Sub-Q), Warfarin (PO)
• Pregnancy Safety: Heparin (safe), Warfarin (teratogenic)
• Onset: Heparin (rapid), Warfarin (slow)
• Monitoring: Heparin (aPTT), Warfarin (INR)
• Antidotes: Heparin (Protamine sulfate), Warfarin (Vitamin K)
• Both increase bleeding risk

Conclusion

• For further information, refer to pharmacology flashcards.
• Encouragement for further study for future nurses.