Q2i: Mechanism of action of drugs used to promote haemostasis

Topical

  • Glue → FIBRIN GLUE
    • 2 separate components freeze dried
      1. Clotting proteins (fibrinogen, F XII, fibronectin)
      2. Dried thrombin
    • Mixed & applied to wound for surgical haemostasis & prevents local bleeding
    • Overall ↑fibrinogen → fibrin (stable clot)
  • Adrenaline α1 = VC
    • Stimulates COX pathway → ↑ADP → ↑platelet aggregation

Factor Replacement

  • Prothrombinex → F II, IX, X
  • F VIIa
  • F VIII → haemophilia A
  • F IX → haemophilia B

Desmopressin

  • Used in vWF disease, uremic? Bleeding, haemophilia A, platelet disorders
  • Acts on ENDOTHELIAL VASOPRESSOR receptors
  • Through cAMP signalling:
    • ↑VWF release
    • ↑VIII levels
    • ↑tPA → VD

NB: uremia impacts platelet activation & aggregation

  • Reinforcing platelet plug & clotting cascade

Vitamin K

  • Fat soluble vitamin
  • Essential co-factor for y. CARBOXYLATION of Protein C/S, Factor II, VII, IX, X
  • ∴activates clotting factors to promote conjugation

Protamine

  • Positively charged alkaline protease complexes bind the negatively charged acidic heparin & form a stable complex completely devoid of any anticoagulant activity

Tranexamic Acid

  • Binds REVERSIBLY to plasminogen lysine binding sites
  • Competitively inhibits plasminogen → plasmin
  • ∴stops clot lysis
  • At high doses, inhibits PLASMIN

Oestrogen

  • Inhibits Protein C (natural anticoagulant)