BLOOD: HEPARINS Flashcards
1
Q
HEPARINS: INDICATIONS
A
- Venous thromboembolism (VTE): low molecular weight heparin (LMWH) is the first choice agent for pharmacological VTE prophylaxis in hospital inpatients, and for initial treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE)
- Acute coronary syndrome (ACS): LMWH or fondaparinux are part of first-line therapy to improve revascularisation and prevent intracoronary thrombus progression
2
Q
HEPARINS: MOA
A
- Thrombin and factor Xa are components in the final common coagulation pathway = formation of a fibrin clot
- Inhibiting their FXN = heparins and fondaparinux prevent the formation and propagation of blood clots.
- Unfractionated heparin (UFH) activates antithrombin that, in turn, inactivates clotting factor Xa and thrombin
- Low molecular weight heparins such as dalteparin and enoxaparin have a similar mechanism of action but preferentially inhibit factor Xa
- Low molecular weight heparins have a more predictable effect and, unlike UFH, do not usually require laboratory monitoring. Consequently, LMWHs are now preferred in most indications
3
Q
HEPARINS: ADVERSE EFFECTS
A
- Bleeding
- Injection site Rxns
- Heparin induced Thrombocytopenia
- Immune rxn less likely with LMWH and fondaparinux than UFH
4
Q
HEPARINS: WARNINGS
A
- Clotting disorders
- Severe uncontrolled HTN
- Recent surgery/trauma
- Heparins avoided around the time of invasive procedures (eg spinal anaesthesia, LP)
- Renal Impairment - LMWH + Fondaparinux can accumulate = use UFH
5
Q
HEPARINS: INTERACTIONS
A
- Combining increases the risk of bleeding
- use of LMWH while initiating warfarin, or the use of antiplatelet drugs (e.g. aspirin, clopidogrel) with fondaparinux/LMWH in ACS
- In major bleeding associated with heparin therapy, protamine can be given to reverse anticoagulation. This is effective for UFH but much less so for LMWH. It is ineffective against fondaparinux.
6
Q
HEPARINS: EXAMPLES
A
- enoxaparin
- dalteparin
- unfractionated heparin
