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Pharm II MHM - Exam 2 > Anticoagulants Carey Lecture > Flashcards

Anticoagulants Carey Lecture Flashcards

1
Q

What are the categories of antithrombotics?

A
  • Anticoagulants
  • Fibrinolytics
  • Antiplatelets
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2
Q

What do anticoagulants do?

A

Stop clot formation and extension

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3
Q

What do fibrinolytics do (in general)?

A

Break up existing clots

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4
Q

What do antiplatelets do?

A

Decrease platelet activation and aggregation

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5
Q

What are the two types of thrombi and how do they differ?

A
  • White thrombus (platelet rich, forms in arteries, MI)

- Red thrombus (fibrin/RBC rich, forms in veints, DVT/PE)

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6
Q

What does TXA2 do?

A

Vasoconstriction

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7
Q

What does vWF do?

A

Binds to exposed collagen fibers at the injured vessel surface

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8
Q

What does fibrinogen do?

A
  • Forms bridges between adjacent platelets

- This results in an aggregate of platelets at the vessel injury site

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9
Q

What does thrombin (factor IIa) do?

A

Converts fibrinogen to fibrin (which forms the stable clot)

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10
Q

What is the final result of the coagulation cascade?

A

Fibrin threads create a plug to make a stable clot

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11
Q

What are the overall steps of platelet activation?

A
  • Injury
  • Collagen and vWF exposed
  • Platelet adherence and activation
  • Binding of fibrinogen
  • Aggregation and plug formation
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12
Q

What are the mediators of platelet aggregation?

A

TXA2
ADP
5-HT

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13
Q

What are the pathways of the coagulation cascade and how are they activated?

A
  • Intrinsic (activated by exposed endothelium)
  • Extrinsic (activated by tissue damage)
  • Common (intrinsic and extrinsic merge together)
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14
Q

What is the first step in the common pathway of coagulation?

A

Activation of Factor Xa

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15
Q

What is the last step in the intrinsic and extrinsic pathways of coagulation?

A

Activation of Factor Xa

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16
Q

What factors are necessary to form a clot?

A 
Factor 2 (prothrombin)
Factor 10
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17
Q

What does Factor Xa do in the coagulation cascade?

A

Combines with Factor 2 (prothrombin) to form thrombin

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18
Q

What factors are targeted by Warfarin?

A

SNOT

Seven, Nine, Ten (0), Two

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19
Q

What does prothrombin time (PT) measure?

A

Activity of Factors 2, 7, 9, 10

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20
Q

What is INR?

A
  • International Normalized Ratio

- Same as PT but standardized worldwide

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21
Q

What does PTT measure?

A

Activity of Factors 2, 5, 7, 9, 10, 11, 12

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22
Q

What is activated clotting time (ACT)?

A
  • Same as PTT but used in invasive/operating procedures

- Quicker result turnaround

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23
Q

What are the indirect thrombin inhibitors?

A

Heparin
LMWH (Enoxaparin)
Fondaparinux

24
Q

How do indirect thrombin inhibitors act as anticoagulants?

A

Help antithrombin deactivate clotting factors

25
Q

Heparin inhibits which clotting factors?

A

X and II

26
Q

What is HIT?

A
  • Heparin Induced Thrombocytopenia
  • Antibody mediated adverse effect of heparin
  • Strong a/w thrombosis
27
Q

What are signs of HIT?

A
  • Platelets fall more than 50% from baseline with nadir 20,000+
  • Platelets start to fall on day 5-10 of therapy
  • Thrombosis occurs while on heparin
  • R/o other causes of thrombocytopenia
28
Q

What is the treatment of HIT?

A
  • Stop heparin, treat with IV direct thrombin inhibitor
  • Do NOT give platelets
  • Do NOT give warfarin until platelets return to normal
29
Q

LMWH (enoxaparin) inhibits which factors?

A

Factors Xa, IIa

30
Q

When should enoxaparin dose be reduced? When should it be stopped?

A
  • Reduced in CrCl 20-30 ml/min

- Stopped in CrCl less than 20

31
Q

What is fondaparinux and what does it do?

A
  • Synthetic pentasaccharide

- Inhibits factor Xa via antithrombin

32
Q

When should dose of fondaparinux be reduced? When should it be stopped?

A
  • Reduced if CrCl less than 50

- Stopped if CrCl less than 30

33
Q

How are indirect thrombin inhibitors reversed?

A
  • Discontinue drug
  • Give protamine sulfate by IV
  • Fondaparinux has NO reversal agent!
34
Q

What are the direct Xa inhibitors?

A
  • Rivaroxaban
  • Apixaban
  • Edoxaban
35
Q

When should rivaroxaban dose be reduced? When should it be stopped?

A
  • Reduced if CrCl 15-50 (AF)
  • Stopped if CrCl less than 30 (VTE)
  • Do NOT use in severe hepatic dysfunction
36
Q

When should apixaban NOT be used?

A

Severe hepatic and renal dysfunction

37
Q

When should edoxaban be reduced? When should it be stopped?

A
  • Reduce if CrCl less than 50
  • Stop if CrCl less than 15, greater than 95
  • Do NOT use in moderate or severe hepatic dysfunction
38
Q

What are the direct thrombin inhibitors and which route are they given?

A
  • Bivalirudin (IV)
  • Argatroban (IV)
  • Dabigatran (oral)
39
Q

How do direct thrombin inhibitors and antithrombin interact?

A

DTIs act independent of antithrombin

40
Q

When should bivalirudin dose be reduced?

A
  • CrCl less than 30

- Hemodialysis

41
Q

When should dabigatran be reduced? Stopped?

A
  • Reduce if CrCl 15-30 (AF)

- Stop if CrCl less than 15 (AF) or less than 30 (VTE)

42
Q

What does warfarin inhibit?

A
  • Factors 2, 7, 9, 10

- Proteins C and S

43
Q

How should warfarin be dosed initially?

A
  • Start low

- 5 mg daily

44
Q

When should warfarin be started at 2.5 mg daily?

A
  • 75+ yo
  • Hepatic insufficiency
  • Critically ill
45
Q

If INR is less than goal two times, how should warfarin dose be adjusted?

A

Increase WEEKLY dose 10-20%

46
Q

If INR is higher than goal two times, how should warfarin dose be adjusted?

A

Decrease WEEKLY dose 10-20%

47
Q

When should INR goal be 2.5 to 3.5?

A
  • Mechanical mitral valve
  • Any mechanical valve with risk factors (AF, HF, MI, embolism)
  • Pts with predisposition for clotting who had a clotting event when INR was at 2-3
48
Q

What are examples of drugs that interact with warfarin to increase INR?

A
  • Amiodarone
  • Bactrim
  • Cipro
  • Metronidazole
49
Q

What are examples of drugs that interact with warfarin to decrease INR?

A
  • Cigs
  • Rifampin
  • St. John’s wort
50
Q

When warfarin is stopped, how long does it take to return to baseline? How about if Vit K is given?

A

About 5 days

about 1 day with Vit K

51
Q

How should Vit K be given to reverse warfarin?

A
  • Oral route is preferred (better absorption)

- Do NOT use SC or IM (erratic absorption)

52
Q

How should IV Vit K be administered?

A
  • 10 mg always diluted with 50 mL NS

- Administer over 10-30 mins

53
Q

Which anticoagulants have CYP interactions?

A

Rivaroxaban and apixaban

*Warfarin

54
Q

Which anticoagulants have P glycoprotein interactions?

A
  • Rivaroxaban
  • Apixaban
  • Edoxaban
  • Dabigatran
55
Q

Which anticoagulants have reversal agents?

A
  • Warfarin (Vit K)
  • Heparin (Protamine)
  • LMWH (Protamine)
56
Q

Which anticoagulant is not good to use in poor OR excellent kidney function?

A

Edoxaban

Pharm II MHM - Exam 2 (5 decks)

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