Heparins

Question 1

What are some examples of heparins

Answer 1

Enoxaparin + dalteparin (LMWHs), unfractioned heparin

Question 2

What are the common indications of use

Answer 2

• Venous thromboembolism (VTE) –> LMWH = 1st line for prophylaxis + initial Tx DVT + PE
• Acute coronary syndrome - LMWH + fondaparinux = 1st line for revascularisation + prevent intracoronary thrombus progression

Question 3

What are the mechanisms of action

Answer 3

• Inhibit Thrombin + Factor Xa (final components of common coag pathway –> prevents formation fibrin clot)
• Unfractioned heparin –> activates antithrombin –> inactives factor Xa + thrombin

LMWH - similar but preferential inhibition factor Xa

Fondaparinux - synthetic compound similar to heparin –> inhibits factor xa only

Question 4

What are the side effects

Answer 4

• Bleeding (risk lower in fondaparinux)
• Injection site reaction
• Heparin-induced-thrombocytopenia (low platelet count)

Question 5

What are some contraindications

Answer 5

CAUTION

• Clotting disorder
• Severe uncontrolled hypertension
• Recent surgery or trauma
• renal impairment - accumulate

AVOIDED - invasive procedures (e.g. LP or spinal anaesthesia)

Question 6

What are some interactions

Answer 6

• Shouldn’t be combiend with other anti-thrombotic medication unless reason
  e. g. use of LMWH when initiating warfarin

Question 7

What can be given to reverse anti-coagulation

Answer 7

Protamine (effective for UFH but less in LMWH + not at all in fonaparinux)