Wk 14 Anti-Coagulants and Anti-Platelets

Question 1

1. What are the two stages of hemostasis?

Answer 1

Formation of platelet plug, reinforcement of platelet plug with fibrin (Coagulation)

Question 2

2. How does heparin work as an anticoagulant?

Answer 2

Assists antithrombin in inactivating thrombin & factor Xa

Question 3

3. How does warfarin work as an anticoagulant?

Answer 3

Decreases synthesis of clotting factors dependent on vitamin K

Question 4

4. How do thrombolytic drugs work?

Answer 4

Promote conversion of plasminogen to plasmin

Question 5

5. Arterial thrombi cause what kind of injury?

Answer 5

Local injury

Question 6

6. Venous thrombi cause what type of injury

Answer 6

Distal injury

Question 7

7. Name the three categories of drugs for thromboembolic disorders? Where in the vascular system do they work?

Answer 7

Anticoagulants - veins
Antiplatelet agents - arteries
Thrombolytics – veins or arteries

Question 8

8. What factors does heparin deactivate? What does this prevent?

Answer 8

Assists antithrombin in deactivating thrombin & factor Xa to prevent more venous thrombi.

Question 9

9. What factor do low molecular weight anticoagulants deactivate?

Answer 9

Factor Xa

Question 10

10. Which anticoagulant can be given during pregnancy?

Answer 10

Heparin

Question 11

11. What is the antidote for heparin?

Answer 11

Protamine sulfate

Question 12

12. Which lab is used to monitor heparin? What is the recommended range?

Answer 12

aPTT 1.5-2X the control

Question 13

13. What potentially-fatal disorder occurs with heparin?

Answer 13

Heparin induced thrombocytopenia (HIT)

Question 14

14. List contraindications to heparin.

Answer 14

Thrombocytopenia; uncontrollable bleeding; surgery of eye, brain, or spinal cord; lumbar puncture or regional anesthesia

Question 15

15. List signs and symptoms indicative of bleeding?

Answer 15

Decreased BP, increased HR, bruises, petechiae, hematomas, red or black/tarry stools, discolored/cloudy urine, pelvic pain from ovaries, headache or faintness, lumbar pain from adrenal gland

Question 16

16. Discuss the proper administration of heparin SubQ.

Answer 16

Lower abdomen, rotate sites; no rubbing; no aspiration; 2” from umbilicus; 25-26 gauges, ½ to 5/8 needle; gentle, firm pressure for 1-2 min after.

Question 17

17. List drugs which may increase bleeding with heparin.

Answer 17

ASA, antiplatelet drugs, NSAIDS, glucocorticoids

Question 18

18. What is the antidote for low molecular weight anticoagulants?

Answer 18

Protamine sulfate

Question 19

19. How does warfarin work?

Answer 19

Interferes with synthesis of Vitamin K-dependent clotting factors

Question 20

20. Where in the vascular system does warfarin work?

Answer 20

Veins

Question 21

21. How is warfarin distributed? Can it enter the placenta or breast milk?

Answer 21

Highly-protein bound, crosses placenta and enters breast milk

Question 22

22. What lab is used to monitor warfarin therapy? What is the suggested range?

Answer 22

PT & INR; INR 2-3 (3-4.5 if mechanical heart valve or recurrent systemic embolism)

Question 23

23. Which anticoagulant is Pregnancy Category X?

Answer 23

Warfarin (Coumadin)

Question 24

24. What is the antidote for warfarin?

Answer 24

Vitamin K (phytonadione)

Question 25

25. List contraindications to warfarin.

Answer 25

Active bleeding; severe thrombocytopenia; decreased synthesis of vitamin K (alcoholism, Vitamin K deficiency, liver disease); surgery of eye, brain, & spinal cord; lumbar puncture or regional anesthesia; pregnancy & lactation

Question 26

26. What would you tell a patient on warfarin who wants to take Tylenol?

Answer 26

Need to monitor INR - 4 tablets a day for one week can increase risk of elevated INR by 10X (May need to lower warfarin dose)

Question 27

27. What two drugs increase the synthesis of Vitamin K dependent clotting factors?

Answer 27

Vitamin K, oral contraceptives

Question 28

28. What foods are high in vitamin K?

Answer 28

Spinach, kale, lettuce, turnips, greens, cabbage, watercress, peas, asparagus, broccoli, oats, whole wheat, green tea, mayonnaise, canola oil, soybean oil.

Question 29

29. How does dabigatran (Pradaxa) work?

Answer 29

Directly binds thrombin, which prevents fibrin formation and activation of factor VIII.

Question 30

30. What are the advantages of dabigatran (Pradaxa) over warfarin? Disadvantages?

Answer 30

Less bleeding, faster onset, no blood work, fewer food interactions, dosing not based on lab or weight. GI distress, no antidote, less experience, BID dosing.

Question 31

31. How does rivaroxaban (Xarelto) work?

Answer 31

Directly inhibits Factor Xa, which prevents fibrin formation.

Question 32

32. In what part of the vascular system do antiplatelet agents work?

Answer 32

Arteries

Question 33

33. List three classes of antiplatelet agents.

Answer 33

ASA, P2Y12ADP receptor antagonists, glycoprotein IIb/IIIa receptor antagonists

Question 34

34. How does aspirin work? How long are platelets affected?

Answer 34

Inhibits COX-1, decreasing platelet aggregation and vasoconstriction. 7-10 days

Question 35

35. How do ADP receptor antagonists work? How long are platelets affected?

Answer 35

Block ADP receptors and prevents platelet aggregation (clopidogrel- Plavix). 5 days.

Question 36

36. What is a significant adverse blood dyscrasia that may be caused by the ADP receptor antagonist, clopidogrel (Plavix)? What drugs may prevent its action?

Answer 36

Thrombotic thrombocytopenia purpura (TTP). Proton inhibitors may inhibit CYP2C19, which activates Plavix.

Question 37

37. How do GP IIb/IIIa receptor antagonists work? Size of effect?

Answer 37

Blocks GP IIb/IIIa receptors & prevents fibrinogen bridges. Large effect, because final step in platelet aggregation.

Question 38

38. What is the major adverse effect of thrombolytic therapy?

Answer 38

Serious bleeding