Q2i: Mechanism of action of drugs used to promote haemostasis
Topical
- Glue → FIBRIN GLUE
- 2 separate components freeze dried
- Clotting proteins (fibrinogen, F XII, fibronectin)
- 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)