Blood

Difference between anticoagulants and antiplatelet

  • Anticoagulants slow down clotting reduce fibrin formation and prevent clots from forming and growing.
  • Antiplatelet stop platelets from clumping and clots forming and growing

Anticoagulants

Heparin- Come from a family of sulphated glycosaminoglycans. Subcutaneous with immediate action and inactivated factors II and X

Low molecular weight heparin is started immediately if the INR is less that 2. Bemiparin, dalteparin, enoxaparin and tinzaparin.

Unfractioned heparin–> is an alternative to low molecular weight heparin or fondaparinux.

NOTE: LMWH exert an anticoagulant activity primarily through the inhibition of factor Xa. It also has a longer plasma half-life than unfractionated heparin. This means that it only needs to be administered once or twice daily without monitoring and it is administered less often than unfractioned heparin.

Also limited effect on platelet activation and lower reported incidence of heparin induced thrombocytopenia

Vitamin K Antagonists– stop from blood clotting  Example Warfarin. Also, drugs ending in coumon or cou(marolant). Essential for hepatic synthesis of factor II, VII, IX and X

If too much warfarin is given Vitamin K can be given to reverse the effects of the toxicity of the narrow therapeutic index drug.

NOAC’s- New oral anticoagulants

  • Apixaban
  • Rivaroxaban
  • Edoxaban
  • Dabigatran

Rivaroxaban, apixaban and edoxaban are all under the class of factor Xa inhibitors. They are anticoagulants. But Dabigatran works directly by inhibiting the formation of thrombin (like Bivalirudin and Fondaparinux) and the effects of Dabigatran can be reversed by Idarucizumab (monoclonal antibody)

Antiplatelet

  • Aspirin
  • Clopidogrel
  • Prasugrel
  • Ticagrelor

Thrombolytics (fibrinolytic)

Thrombolytic drugs break down thrombosis –arterial/venous and fibrinolytic drugs break down fibrinogen and fibrin.

Below list of some drugs

  • Streptokinase (activates plasminogen, from cultures of streptococci)
  • Urokinase is licensed to restore the patency of occluded intravenous catheters and cannulas blocked with fibrin clots.

Below is the list of Tissue plasminogen activators (t-PA)

  • Alteplase
  • Reteplase
  • Tenecteplase

They promote plasminogen to break down to plasmin that will act to dissolve the plasmin

Reteplase and tenecteplase is lisenced for MI (with ST elevation and within 12 hours of onset).

Alteplase, streptokinase and urokinase can be given for DVT (DVT test: D Dimer). Alteplase can also be given for ischaemic stroke.

Blood clot promoting drugs

Anti-fibrinolytic drugs are blood clot promoting drugs. Examples include:

  • Aprotinin
  • Tranexamic acid (analogue of aminocaproic acid)
  • Epsilon-aminocaproic acid
  • Aminomethylbenzoic acid