Antithrombotic drugs overview

Question 1

composition of venous thrombi and treatment

Answer 1

composed mainly of fibrin and trapped red blood cells with relatively few platelets. Treat with anticoagulation

Question 2

composition of arterial thrombi and treatment

Answer 2

composed mainly of platelet aggregates held together by small amounts of fibrin. Treat with antiplatelet therapy

Question 3

Uses of anticoagulant agents

Answer 3

Drugs of choice for prevention and treatment of venous thromboembolism and for prevention of cardioembolic events in patients with atrial fibrillation. Anticoagulants are also effective for arterial thrombosis and their effects can be additive with antiplatelet agents

Question 4

uses of antiplatelet agents

Answer 4

Drugs of choice primarily for prevention and treatment of arterial thrombosis (primary and secondary prevention and treatment of acute coronary syndrome).

Question 5

Drugs used for stable angina

Answer 5

anti-anginal agents (nitrates, BB), anti-hypertensives, statins, anti-platelet (aspirin)

Question 6

drugs used to treat coronary heart disease

Answer 6

statins, anti-platelet (aspirin, clopidogrel), anti-anginal (nitrates, BB, Ca channel blockers), LV dysfunction (ACEI, ARBs)

Question 7

Drugs used for primary prevention of acute coronary syndrome

Answer 7

antiplatelet: Aspirin (if risk factors present), asprin (if no risk factors but >45 yrs men, >65 yrs in women)

Question 8

Secondary prevention of recent MI and ischemic stroke

Answer 8

Recent MI: aspirin (clopidogrel if intolerant). Ischemic stroke: asprin +/- clopidogrel

Question 9

Drugs used for unstable angina/ Non-ST elevated MI

Answer 9

antiplatelet +/- anticoag: Aspirin, ± clopidogrel or prasugrel or ticagrelor, ± UFH or LMWH or fondaparinux, ± GPIIb/IIIa inhibitor (IV nitroglycerin, BB, catheter)

Question 10

Drugs used for acute MI (ST elevated MI)

Answer 10

Antiplatelet and anticoag: Aspirin, + clopidogrel or prasugrel or ticagrelor, + UFH or LMWH or fondaparinux, ± GPIIb/IIIa inhibitor (nitroglycerin and BB)

Question 11

Drugs used for Percutaneous coronary intervention

Answer 11

Antiplatelet and anticoag: Aspirin + clopidogrel or prasugrel or ticagrelor, + UFH or LMWH or bivalirudin, ± GPIIb/IIIa inhibitor

Question 12

Drugs used for atrial fibrillation

Answer 12

Anticoagulant and antiplatelet: Warfarin or dabigatran or rivaroxaban or apixaban (aspirin can be used for patients at low risk)

Question 13

Drugs for treatment of venous thromboembolism

Answer 13

Anticoag: LMW heparin, or Unfractionated heparin or fondaparinux + warfarin

Question 14

Drugs for VTE prevention

Answer 14

Anticoagulation. Hospitalized: Low-dose UFH or LMWH or fondaparinux. General surgery: Low-dose UFH or LMWH or fondaparinux. Orthopedic surgery: Fondaparinux or rivaroxaban or dabigatran or LMWH or warfarin

Question 15

Drugs for peripheral aterial disease

Answer 15

Aspirin

Question 16

Coagulation involves what 4 components

Answer 16

endothelial cells of vasculature, circulating platelets, coagulation factors, fibrinolytic system

Question 17

Mechanism of blood coagulation

Answer 17

Blood emerges and damage to vessel exposes collagen of subendothlium > Vasoconstriction mediated by vasoactive substances released by platelets > adhesion of platelets to damaged endothelium (via collagen and vWF) plus platelet aggregates > Platelets are activated and release thromboxan A2, ADP, which causes more platelet adhesion/aggregation >thrombus plug forms > Fibrin is deposited on platelets and coagulation occurs > fibrinolysis digests the clots (plasmin)

Question 18

Describe coagulation cascade

Answer 18

Tissue damage exposes tissue factor > Xa is activated > Xa catalyzes prothrombin to thrombin > thrombin catalyzes fibrinogen to fibrin > fibrin reinforces aggregated platelet plug

Question 19

What does aPTT measure?

Answer 19

Intrinsic pathway - used to monitor heparin therapy

Question 20

What does PT measure?

Answer 20

Extrinsic pathway- used to monitor warfarin therapy

Question 21

What does Ecarin clotting time measure?

Answer 21

Monitors anticoag therapy with direct thrombin inhibitors

Question 22

What does Prostacyclin and NO do?

Answer 22

). Reverse vasoconstriction and inhibit platelet aggregation

Question 23

Mechanisms for fibrin inhibition

Answer 23

Antithrombin III: Serine protease inhibitor that binds to and inactivates IIa, IXa, Xa, XIIa. This activity is greatly accelerated by the endothelial cell surface and by heparin. Protein C/S: Activated protein C (with cofactor protein S ) inactivates factors Va and VIIIa, diminishing rate of prothrombin and factor X activation

Question 24

Fibrinolysis

Answer 24

Plasmin activation by tissue plasminogen activator proteolyzes fibrin and limits thrombosis