Heparin
Increases the ability of antithrombin molecule to irreversibly inhibit thrombin, IXa, Xa, XIa.
LMWH - mainly inhibits FXa only, less monitoring needed. Sub-cut inj. Unfractionated - continuous infusion, monitor aPTT ratio, uncommon can cause HIT (heparin induced thrombocytopenia)
- Chronic use (\rightarrow) osteoporosis
- Reverse effects with protamine sulphate
Warfarin
Vitamin K antagonist with lots of interactions with drugs and food. FII, VII, IX, X, protein C +S all vit K dependant.
- Monitor INR (\approx) PT ratio
- Start on LMWH at same time to prevent Warfarin induced skin necrosis
- Antidote: prothrombin complex concentrate - raises inhibitor factors + vit K
Direct oral anticoagulants
Predictable dose response and minimal interactions unlike Warfarin. Fast onset and offset. Cannot use with mechanical heart valves
Factor X inhibitors - -xaban eg rivaroxaban Direct thrombin inhibitors - dabigatran