anticoagulants, antiplatelet and thrombolytics 1

Question 1

what is virchows triad

Answer 1

• Flow is distributed or impeded
• Vessel or heart wall has damaged endothelium
• Clotting factors or blood platelets increased (hypercoagulability) (anticoagulant, antiplatelet and thrombolytic drugs act on this)

Question 2

what are the types of anticoagulatns

Answer 2

Vit. K antagonists (warfarin), heparin, thrombin inhibitors (dabigatrin), factor X inhibitors (rivaroxaban)

Question 3

describe warfarin

Answer 3

Vit K exists as two broad forms K-Oxidised (epoxide) and K-reduced. Carboxylase is needed for conversion of decarboxy-prothrombin to prothrombin needs a cofactor to do this K-reduced gives up electrons and allows change. Results K-oxidised and then it cycles back again. Warfarin is an inhibitor of VKORC1. Results Vit K is trapped and prothrombin is run down. Factor 2, 7,9 and 10 also need this change.

Question 4

what is the problem with warfarin?

Answer 4

teratogenic, protein S and C heritable def, increase bleeding risk, drug interactions

Question 5

how does heparin work

Answer 5

• inactivation of Xa and thrombin. - Binds to lysine on AT3 conformational change caused increased affinity for activated factors of intrinsic arm (esp. Xa and thrombin) accelerated inactivation prevent conversion of fibrinogen to fibrin stops clot propagation

Question 6

what are the adverse effects of heparain

Answer 6

bleeding, immune-mediated platelet activation (thrombosis, bleeding from thrombocytopenia rare).