Antiplatelet and Anticoagulant drugs

Question 1

What is hemostasis?

Answer 1

The process of stopping bleeding while maintaining blood flow.

Question 2

What are the four steps of hemostasis?

Answer 2

1) Vasoconstriction
2) Primary Hemostasis
3) Secondary Hemostasis
4) Fibrinolysis

Question 3

Which molecule causes vasoconstriction at the injury site?

Answer 3

Endothelin (released from endothelial cells).

Question 4

What do platelets bind to at the injury site?

Answer 4

von Willebrand factor (vWF) & collagen.

Question 5

What happens when platelets are activated?

Answer 5

They change shape, degranulate, and release ADP & TXA2.

Question 6

What is the role of ADP & TXA2?

Answer 6

They recruit & aggregate more platelets to form a platelet plug.

Question 7

What stabilizes the platelet plug?

Answer 7

Fibrin (formed via coagulation cascade).

Question 8

Which key coagulation factors are involved?

Answer 8

Factor X, Factor II (thrombin), and Factor I (fibrinogen).

Question 9

What enzyme breaks down the clot?

Answer 9

Plasmin.

Question 10

Which enzyme activates plasmin from plasminogen?

Answer 10

Tissue plasminogen activator (t-PA).

Question 11

What causes arterial thrombosis?

Answer 11

Atherosclerotic plaque rupture or erosion.

Question 12

Which process is primarily involved in arterial thrombosis?

Answer 12

Platelet activation.

Question 13

What conditions are associated with arterial thrombosis?

Answer 13

Heart attacks (myocardial infarction), strokes, peripheral vascular disease.

Question 14

What type of drugs are used for prevention/treatment arterial thrombosis?

Answer 14

Antiplatelet drugs (e.g., aspirin, clopidogrel).

Question 15

What causes venous thrombosis?

Answer 15

Thrombophlebitis (inflammation of vein walls) or static blood flow.

Question 16

Which process is primarily involved in venous thrombosis?

Answer 16

Activation of the coagulation cascade.

Question 17

What conditions are associated with venous thrombosis?

Answer 17

Deep vein thrombosis (DVT) and pulmonary embolism.

Question 18

What type of drugs are used for prevention/treatment of venous thrombosis?

Answer 18

Anticoagulants (e.g., heparin, warfarin, rivaroxaban).

Question 19

What enzyme produces TxA2?

Answer 19

COX-1 enzyme from arachidonic acid.

Question 20

What is the function of TxA2?

Answer 20

Promotes platelet activation and aggregation.

Question 21

How does aspirin affect TxA2?

Answer 21

Aspirin irreversibly inhibits COX-1, preventing TxA2 synthesis and reducing platelet activation.

Question 22

Where is Adenosine Diphosphate released from?

Answer 22

Activated platelets.

Question 23

What is the function of Adenosine Diphosphate in platelet activation?

Answer 23

Binds to ADP receptors to mediate calcium release and enhance platelet activation.

Question 24

How does clopidogrel (Plavix) work?

Answer 24

Antagonizes ADP receptors on platelets, preventing ADP-mediated activation.

Question 25

What is the role of Factor X in the coagulation cascade?

Answer 25

Links the intrinsic and extrinsic pathways to the common pathway by converting to active Xa.

Question 26

How is thrombin (Factor IIa) generated?

Answer 26

Factor Xa activates prothrombin (Factor II) to thrombin (Factor IIa).

Question 27

What is the function of thrombin?

Answer 27

Converts fibrinogen (Factor I) into fibrin, forming a stable clot.

Question 28

How does the coagulation cascade contribute to thrombosis?

Answer 28

Converts soluble fibrinogen to insoluble fibrin strands, stabilizing the platelet plug into a thrombus.

Question 29

What happens in pathological conditions with excessive coagulation activation?

Answer 29

Can lead to harmful clot formation, increasing the risk of stroke, heart attack, or deep vein thrombosis.

Question 30

What are the advantages of warfarin?

Answer 30

Oral administration. Has an antidote (vitamin K).

Question 31

What are the disadvantages of warfarin?

Answer 31

Delayed onset (72hrs to peak). Requires monitoring (PT-INR). Many drug/food interactions. Variable effectiveness between patients.

Question 32

What are the advantages of rivaroxaban?

Answer 32

Fixed dosing, no monitoring needed. Few drug interactions. Rapid onset. Predictable effect.

Question 32

What is the mechanism of warfarin?

Answer 32

Inhibits vitamin K-dependant clotting factors

Question 33

What are the disadvantages of rivaroxaban?

Answer 33

No readily available antidote. Still carries bleeding risk.

Question 34

What is the mechanism of rivaroxaban?

Answer 34

Direct factor Xa inhibitor

Question 35

What are the advantages of heparin?

Answer 35

Immediate effect. Can be used in kidney/liver disease. Has an antidote (protamine).

Question 36

What are the disadvantages of heparin?

Answer 36

Requires injection/IV. Short half-life (1hr). Risk of thrombocytopenia. Allergic reactions possible (animal product).

Question 37

What is the mechanism of heparin?

Answer 37

Enhances antithrombin activity to inhibit factor Xa and thrombin

Question 38

What conditions are antiplatelet drugs used to prevent?

Answer 38

Arterial thrombosis (e.g., stroke, heart attack, coronary artery disease).

Question 39

What conditions are anticoagulant drugs used for?

Answer 39

Deep venous thrombosis (DVT). Atrial fibrillation. Pulmonary embolism. Mechanical heart valves. Knee/hip replacement therapy. Myocardial infarction.

Question 40

What is the bleeding risk for patients on anticoagulants and antiplatelet drugs?

Answer 40

Prolonged bleeding after dental procedures.

Question 41

Why should NSAIDs be avoided with anticoagulants and antiplatelet drugs?

Answer 41

Increased risk of gastrointestinal bleeding.

Question 42

What can alter warfarin levels?

Answer 42

Antibiotics, antifungals, and pain meds can affect warfarin levels, requiring dose adjustments.

Question 43

Key Takeaways for Dental Practice

Answer 43

Assess bleeding risk before procedures. Coordinate with physicians for patients on anticoagulant therapy. Consider local hemostatic measures (e.g., sutures, tranexamic acid) for surgical procedures. Educate patients on bleeding risks and signs of complications. May require medication adjustment/discontinuation Consider alternative pain medications to NSAIDs Be aware of herbal supplements that affect bleeding risk