Heparin

• Facts:
  Increases PTT, activates antithrombin III
  
  Affects intrinsic pathway, decreases fibrinogen level
• Complications:
  Heparin Induced thrombocytopenia
• Notes:
  Must bridge to warfarin because warfarin inhibits proteins C and S before any vitamin K dependent factors (II, VII, IX, X), leading to a period of paradoxical hypercoagulability before proper coagulation
  
  Reversed with protamine sulfate