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MLS Coagulation/Hemostasis > Unit: 5 - Monitoring Antithrombotic Therapies > Flashcards

Unit: 5 - Monitoring Antithrombotic Therapies Flashcards

1
Q

Drugs that break down clots are also called?

A

Thrombolytic drugs

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2
Q

What os VTE?

A

Venous thromboembolic disease; includes DVT & PE

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3
Q

What is DVT?

A

Deep vein thrombosis

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4
Q

What is PE?

A

Pulmonary embolism

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5
Q

What is AMI?

A

Acute myocardial infarction (heart attack)

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6
Q

What is TIA?

A

Transient ischemic attack

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7
Q

What is PAO/PAD?

A

Peripheral artery occlusion or disease

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8
Q

What is NVAF?

A

Non-valvular atrial fibrillation

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9
Q

What are the 4 types of anticoagulant drugs we are studying?

A

Heparin, Coumadin/warfarin, anti-Xa, and DTI (direct thrombin inhibitors)

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10
Q

Coumadin is a vitamin K antagonist (VKA). T or F?

A

True

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11
Q

What enzyme does warfarin/Coumadin act on?

A

It suppresses vit K epoxide reductase

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12
Q

How is Coumadin metabolized?

A

It is metabolized by the CYP450 pathway, which is an enzyme found in the liver

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13
Q

How does knocking out the epoxide reductase enzyme suppress VK dependent coagulation factors?

A

It inhibits the carboxylation/decarboxylation cycle of VK, which makes VK dependent factors remain non-active due to their inability to bind Ca2+

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14
Q

What are the prophylactic uses for coumadin?

A

To prevent VTE and stroke and to help with other chronic medical conditions that may cause clotting

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15
Q

What are the therapuetic uses for Coumadin?

A

After DVT, PE, or AMI

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16
Q

What does an INR in the correct therapeutic range indicate about the patient?

A

The pt is metabolizing the drug properly, the dosage is correct, and the pt is not at risk for either clotting or bleeding.

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17
Q

What is the critical value for INR at DH?

A

Greater than 5

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18
Q

What is an alternative test to INR? Why might it be used instead?

A

Chromogenic FXa Assay (CFX); It is best to use when pt has LA, factor inhibitors, or factor deficiency

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19
Q

What is the therapeutic range for Coumadin at DH?

A

2-3

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20
Q

What does VK do to the effects of coumadin?

A

Reverses them

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21
Q

What is the first step to reverse a Coumadin OD?

A

Discontinue the Coumadin and administer oral or IV VK

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22
Q

What can also be administered for reversal of a Coumadin OD (2 options)? What coag factors does it contain?

A

Prothrombin complex concentrate (PCC) - FII, VII, IX, and X

Activated FVII

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23
Q

With severe bleeding, what should be administered to reverse a Coumadin OD?

A

FFP

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24
Q

What are the three types of heparin used?

A

UFH, LMWH, and Fondaparinux

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25
Q

Where is the antithrombin (AT) binding site on the UFH molecule?

A

The pentasaccharide sequence

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26
Q

Which factors does AT/UFH binding inhibit?

A

FIIa, IXa, Xa, XIa, and XIIa

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27
Q

What are the main uses of UFH?

A

To treat VTE, AMI, after stent placement, and during cardiac bypass surgery

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28
Q

When is LMWH used instead of UFW?

A

To prevent HIT (not to treat a pt who already has HIT)

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29
Q

What tests (4) are used to monitor UFH? How often is it monitored?

A

PTT; 4-6 hours after bolus, and then every 24 hours for up to 2 weeks or until properly adjusted

Plt count to monitor for HIT (<30% change)

Chromogenic anti-Xa heparin assay

ACT - POCT

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30
Q

What is the method used to determine a therapeutic range for each of these medications?

A

Brill Edwards Method (linear regression plot of 2 test methods)

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31
Q

What are two limitations of PTT?

A

Heparin resistance and prolonged baseline PTT

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32
Q

What drug is used to reverse OD with UFH? What is the mechanism? How is it monitored?

A

Protamine sulfate; Binds and neutralizes UFH so that it can’t bind with AT; PTT or ACT and plt count

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33
Q

What is the patented name for LMWH?

A

Lovenox

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34
Q

What is the size difference between LMWH and UFH? What is the benefit of this?

A

LMWH is 1/3 the size of UFH (depolymerized); Shorter TAT

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35
Q

What is the difference in action of LMWH compared to UFH?

A

It only inactivates Xa (not FIIa, IXa, XIa, and XIIa)

36
Q

Why does LMWH only bind and inactivate Xa?

A

Because of the smaller size of the molecule and reduced binding sites available

37
Q

What are the prophylactic uses of LMWH?

A

During or after surgery, After DVT, PE and unstable angina, During pregnancy for women at risk of VTE

38
Q

What is the therapeutic use of LMWH?

A

During surgery after discontinuing Coumadin

39
Q

Which of the two non-synthetic forms of heparin is likely to cause DIC?

A

UFH (not LMWH)

40
Q

How is LMWH therapy monitored?

A

There is usually no need to monitor. For exceptions, perform chromogenic anti-Xa heparin assay to monitor

41
Q

What does the chromogenic Anti-Xa heparin assay measure? How is this different than the PTT test?

A

It measures the concentration of heparin, rather than its anticoagulant effects

42
Q

What are the reagents for the chromogenic Anti-Xa heparin assay?

A

Antithrombin and excess Xa

43
Q

What is the method of the chromogenic Anti-Xa heparin assay?

A

AT binds to heparin, which in turn binds to Xa, excess free Xa digests its substrate to produce a color change which is measured spectrophotometrically.

44
Q

How is the color change interpreted for the chromogenic Anti-Xa heparin assay?

A

Less color means more heparin (less free Xa is available to act on substrate and cause color change)

45
Q

What is used to reverse OD with LMWH? How is it monitored?

A

Protamine sulfate; With anti-Xa assay

46
Q

What is Fondaparinux?

A

A synthetic pentasaccharide sequence of UFH/LMWH

47
Q

What is the action of Fondaparinux?

A

The same as LMWH - inactivates Xa

48
Q

What is the use of Fondaparinux? How is it monitored?

A

To prevent VTE after surgery and to treat VTE; With chromogenic Anti-Xa assay (after establishing therapeutic range)

49
Q

What is used to reverse OD with Fondaparinux?

A

rFVIIa

50
Q

What are the three Anti-Xa drugs?

A

Rivaroxaban, Apixaban, Edoxaban

51
Q

What makes Anti-Xa drugs an attractive alternative to warfarin and LMWH?

A

There is no need for monitoring therapy with these drugs

52
Q

What is Rivaroxaban used for?

A

VTE, prevent stroke with NVAF

53
Q

What is Apixaban used for?

A

NVAF

54
Q

What is Edoxaban used for?

A

NVAF, DVT and PE

55
Q

If Anti-Xa drug therapy needs to be monitored, what tests will be used?

A

PT and chromogenic Anti-Xa assay (calibrated with specific medicine, not heparin)

56
Q

How is OD with Anti-Xa reversed?

A

There is no approved treatment for reversal other than discontinuing the drug

57
Q

What is the alternative anticoagulant for a pt experiencing HIT?

A

Aragatroban

58
Q

What are the three DTIs? Which ones are administered intravenously?

A

Aragatroban, Bivalirudin, and Dabigatran; Aragatroban and Bivalirudin

59
Q

What is the mode of action of DTIs?

A

They bind to clot-bound thrombin and free thrombin

60
Q

What is used to monitor therapy with DTIs?

A

PTT and ACT (for surgery and cath lab) - other options are ECT and Hemoclot

61
Q

What is ECT? What is the mode of action?

A

Ecarin clotting time; Cleaves prothrombin to thrombin (insensitive to heparin, Coumadin and inhibitors such as LA)

62
Q

What are the oral antiplatelet drugs?

A

Aspirin, Clopidogrel, Prasugrel, and Ticagrelor

63
Q

How is aspirin therapy monitored?

A

VerifyNow, Aspirin Works, and Plt aggregation studies

64
Q

What is the mode of action of aspirin?

A

It irreversibly acetylates the COX 1 enzyme in the eicosanoid pathway and inhibits the synthesis of TXA2

65
Q

What is thromboxane B2 used for?

A

It is a stable measurable plasma product that is reduced in aspirin therapy; it can be measured to assess effectiveness of therapy; if there are high levels of TXB2, the aspirin is NOT working efficiently

66
Q

What are oral antiplatelet drugs (besides aspirin) used for? What is their mode of action?

A

They are used following MI or stroke; They bind to P2Y12 plt receptors (which inhibit the binding of ADP and activation of plts)

67
Q

What is PFA-100 used for?

A

It is a rapid method to determine aspirin and clopidogrel responses and VWD

68
Q

What is the principle of the PFA-100 assay?

A

It is a high-shear force dynamic flow system; Collagen is used with either epinephrine of ADP and the time to closure is measured

69
Q

What does it mean if the Col/Epi and Col/ADP PFA-100 tests are both prolonged?

A

The following should be considered: Anemia, thrombocytopenia or significant plt disorder, VWD, BS, GT, storage pool disease, etc.

70
Q

What will be the result of the Col/Epi and Col/ADP PFA-100 tests if the pt is on aspirin or NSAIDs?

A

Col/Epi prolonged & Col/ADP normal

71
Q

What are the IV antiplatelet drugs?

A

Eptifibatide, Abciximab and Tirofiban

72
Q

What is the mode of action of IV antiplatelet drugs?

A

They are anti GPIIa/IIIb

73
Q

What are IV antiplatelet drugs used for ?

A

Cardiac catheterization and stent placement

74
Q

What tests are performed before a pt is started on IV antiplatelet drugs?

A

PT, PTT, and CBC

75
Q

What tests are performed while a pt is on IV antiplatelet drugs?

A

PTT, ACT, and plt count

76
Q

What tests are performed after a pt is on IV antiplatelet drugs?

A

Plt count

77
Q

What is the VerifyNow P2Y12 assay used for?

A

It is a POC light transmittance aggregometry test used to measure P2Y12 receptor blockade for pts who have been on P2Y12 inhibitors

78
Q

How are the light transmittance results for the P2Y12 test interpreted?

A

Increased light transmittance > plts are aggregating (normal)

Less light transmittance > plt aggregation is inhibited

79
Q

What are the three thrombolytic drugs?

A

TPA, Streptokinase and urokinase

80
Q

What is the mode of action of streptokinase?

A

It dissolves fibrin clots

81
Q

What is the mode of action of Urokinase and TPA?

A

They cleave plasminogen to plasmin to initiate fibrinolysis

82
Q

What are the three thrombolytic drugs?

A

TPA, Streptokinase and urokinase

83
Q

What is done in the case of a venous clot?

A

Anticoag or thrombolytic drugs are given, and/or an inferior vena cava filter is placed to help prevent blood clots from traveling to the heart or lungs

84
Q

What is the mode of action of Urokinase and TPA?

A

They cleave plasminogen to plasmin to initiate fibrinolysis

85
Q

What is done in the case of a arterial clot?

A

Catheter-directed thrombolysis and/or surgery to remove the clot

86
Q

Why is it especially important to know the differences in the thromboplastin reagents?

A

If you are trying to detect LA, only certain reagents can be used

MLS Coagulation/Hemostasis (1 decks)

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