Heparins

• Due to their rapid onset of action and reversibility, heparins are usually preferred over oral anticoagulants in situations requiring rapid anticoagulation
• heparins (LMWH) are commonly used during pregnancy due to their established safety profile.
• Unfractionated heparin mechanism of action:

  • Enhances the activity of antithrombin
  • Leads to inhibition of coagulation factors IIa (thrombin) and Xa
  • Prevents the conversion of fibrinogen to fibrin
• Unfractionated heparin indications:

  • UFH is preferred over LMWH in patients with a higher risk of bleeding or renal impairment
  • Shorter half life and more reversibility in comparison to LMWH
  • Acute treatment of VTEs
  • Prophylaxis of VTE in hospitalised patients
• LMWH mechanism of action:

  • Target factor Xa
  • Impede the formation of thrombin
• LMWHs have a reduced risk of certain adverse effects, such as osteoporosis and heparin-induced thrombocytopenia (HIT), making them more appropriate than UFHs in certain patient groups such as in pregnant women.
• LMWH may be preferred in certain scenarios, such as:

  • Acute treatment of venous VTEs including deep vein thrombosis (DVT) and pulmonary embolism (PE)
  • Prophylaxis of VTE in hospitalised patients undergoing surgery or with medical illnesses
  • Treatment and prevention of VTE in pregnant people or individuals with cancer.
• Monitoring:

  • Platelet count - before and during treatment due to risk of HIT
  • Potassium levels
  • Coagulation screen - will effect PT and APTT
• Key interactions:

  • Other anticoagulants
  • Antiplatelet agents
  • NSAIDs
• Key side effects:

  • haemorrhage
  • Hyperkalaemia
  • Heparin-induced thrombocytopenia - 30% reduction in platelet count, skin allergies and increased risk of thrombosis
• Heparin antidote = protamine sulfate