Anticoagulants Flashcards
How are Unfractionated heparin administered?
Parenterally - IV
unfractionated heparins are fast acting but short acting. Why are they short acting?
There are heparinases in the blood that inhibit their action and protamine sulphate can also be used to inactivate the heparin.
What is a possible major side effect of unfractionated heparins?
Thrombocytopenia - massive reduction in platelets (needed to form clots). If it appears in the first 2-3 days - no symptoms but if it reappears after 5-7 days if will do so as an immune mediated response. Need to stop immediately.
Low MW heparins do not inactivate thrombin directly, what do they inactivate?
Factor Xa = in charge of convertin prothrombin to thrombin
What are the advantages of low MW heparins over unfractionated heparins?
They have a slightly longer duration of action and can be administered through deep subcutaneous injection as well as IV = gives patient the option of being able to be delivered at home.
What is the common name used for vitamin K antagonists?
Coumarins
What is the MoA of the coumarins?
Inhibit vitamin K reductase = the reduced from of vit K is the active form. Without vitamin K several factor involved in the clotting cascade aren’t carboxylated.
What are the disadvantages of the coumarins?
Slow onset of action bc some factors will have been carboxylated already (in an emergency would need to administer heparin first)
Enormous range of interactions with drugs that lead to an increase and decrease in anticoagulant effect.
What do we need to balance when considering introducing an anticoagulant?
The risk (bleeding) / benefit (DVT/EMBOLISM)
Other than vitamin K antagonist, what other oral anticoagulant group is there?
NOACS - Non vitamin K antagonists e.g. rivaroxaban
What is the aim of DVT/embolism treatment?
To break down the clot = restore circulation, avoid damage to valves and avoid further DVT/embolism
What would be the first step in treating DVT/embolism?
LMWH i.v unless renal impairment or risk of bleeding - then give UFH
What would be the treatment if someone had a PE and was haemodynamically unstable ( unstable BP or perfusion)?
UFH and then depending on the location of the thrombus consider thrombolytic therapy (drugs + maybe removing the clot)
What needs to be offered to a patient with a confirmed DVT or PE within 24 hours?
Vitamin K antagonist and continue treatment for 3 months after (prophylactically) - risk : benefit needs to e assessed.
What kind of thrombosis are anticoagulants used to treat?
Venous thrombosis - DVT / PE
