DVT Flashcards
1
Q
Heparins and fondaparinux
Common indications
A
- Venous thromboembolism- LMWH is the first choice of agent for pharmacological VTE prophylaxis (enoxaparin) and for the initial treatment of Deep Vein Thrombosis
- Acute coronary syndrome- LMWH or fondaparinux are part of first-line therapy to improve revascularisation and prevent intracoronary thrombus progression
2
Q
Heparins and fondaparinux
Mechanism of action
A
- Thrombin and Factor Xa are key component of the final common coagulation pathway that leads to formation of a fibrin clot
- By inhibiting their function, heparins and fondaparinux prevent the formation and proagation of blood clots
- Unfractioned Heparin (UFH) activates anti-thrombin that, in turn Inactivates clotting factor Xa and thrombin.
- LMWH have a similar MOA but preferentially inhibit factor Xa.
- LMWH have a more predictable effect and unlike UFH do not require laboratory monitoring
-
Fondaparinux- is a synthetic compound that is similar to heparin, it only inhibits Xa
- It appears to have similar efficacy to LMWH and has become the anticoagulant of choice in the treatment of ACS in many hospitals in the UK
3
Q
Heparins and fondaparinux
Adverse effects
A
- The main adverse effect of heparins and fondaparinux is Bleeding
- This risk may be lower with fondaparinux than with LMWH or UFH
- As with many injectables, these frugs may cause Injection site reaction
- Rarely, heparins may cause a dangerous syndrome characterised by low platelet count and thrombosis (Heparin-induced thrombocytopenia)
- This immune reaction is less likely with LMWH and fondaparinux than UFH
4
Q
Heparins and fondaparinux
Warnings
A
- Anticoagulants should be used with caution in patients at increased risk of bleeding: Clotting disorders, severe uncontrolled HTN, surgery/trauma
- Heparins should be avoided around the time of invasive procedures, particularly lumbar puncture and spinal anaesthesia
- In patients with renal impairment, LMWH and fondaparinux may accumulate and should be used at a lower dose or unfractionated heparin used instead
5
Q
Heparins and fondaparinux
Interactions
A
- Combining antithrombotic drugs increase the risk of bleeding
- This should usually be avoided unless there is a special reason for combined therapy, such as in the use of LMWH while initiating warfarin or the use of antiplatelet drugs
- MAJOR BLEEDING risk
6
Q
Heparins and fondaparinux
Prescription
A
- LMWH and fondaparinuc are prescribed for regular administration into hospital
- Prophylaxis of VTE- enox 40mg SC/day
- Treatment of VTE and ACS- higher doses (60-80mg/day)
