Anticoagulants Flashcards

1
Q

What drug classes are used in stable angina?

A

Aspirin

Thienopyridines

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2
Q

What drug classes are used in UA/NSTEMI?

A
Aspirin
Thienopyridines
Glycoprotein IIb/IIIa
Unfractionated heparin
LMW heparin
Factor Xa inhib
Direct thrombin inhib
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3
Q

What drug classes are used in STEMI?

A
Aspirin
Thienopyridines
Glycoprotein IIb/IIIa
Unfractionated heparin
LMW heparin
Factor Xa inhib
Direct thrombin inhib
Fibrinolytic therapy
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4
Q

What drug classes are used in atrial fib?

A

Aspirin
Factor Xa inhibitors
Direct thombin inhibitors
Warfarin

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5
Q

What drug class is used for treatment only of venous thromboembolism?

A

Fibrinolytics

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6
Q

Between what two parts of the coagulation cascade does the most binding occur?

A

Between glycoprotein Ib-IX platelet receptor and von Willebrand factor

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7
Q

What two substances are the most potent platelet activators?

A

Collagen & thrombin

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8
Q

aspirin general indications

A

Indicated for all CHD patients

81-325mg

Clopidogrel 75mg can be used in pts w/ aspirin hypersensitivity

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9
Q

aspirin indications and dosing for acute management

A

162-325mg one time, chewed & swallowed non-enteric coated

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10
Q

aspirin indications and dosing for maintenance

A

81mg PO, enteric coated, indefinitely

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11
Q

Thienopyrdine MOA

A

Anti-platelet: blocks the ADP receptor thus preventing platelet activation

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12
Q

How are thienopyridines dosed before/during and after the PCI?

A

All pts receive a loading dose before/during PCI followed by maintenance dose

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13
Q

What is the difference between 300mg clopidogrel and 600mg clopidogrel?

A

300mg provides adequate antiplatelet activity in 6 hrs, 600mg provides antiplatelet activity in 2 hrs

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14
Q

If CABG is planed, how should thienopyridine meds be managed?

A

Thienopyridines need to be held for 5 (clopidigrel & ticagrelor) to 7 (prasurgrel) days before surgery.

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15
Q

What is the dosage of prasurgrel in pts weighing less than 60kg?

A

5mg

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16
Q

ticlopidine (Ticlid) dosing/indications

A

500mg loading dose
250mg BID maintenance

*can cause neutorpenia

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17
Q

clopidogrel (Plavix) dosing/indications

A

300-600mg loading dose
75mg QD maintenance

contraindication w/ 2C19 inhibitors (omeprazole) & poor metabolizer id’d as CYP2C192 or CYP2C19*3

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18
Q

prasugrel (Effient) dosing/indications

A

60mg loading
10mg QD maintenance

  • 5mg for pts <60kg
  • caution in >75y, stroke/TIA hx
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19
Q

ticagrelor (Brilinta)

A

180mg loading
90mg maintenance

  • can cause hyperuricemia, increased creatinine & ventricular pause
  • caution in gout, 3A inducers/inhibitors, aspirin maintenance >100mg & hepatic impairment
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20
Q

Glycoprotein IIb/IIIa inhib MOS

A

Inhibits the GB IIb/IIIa receptor on platelets preventing the fibrinogen crosslink and platelet aggregation

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21
Q

Glycoprotein IIb/IIIa inhib general indications and dosing

A
  • Reserved for high risk pts w/ ischemic EKG changes or increased cardiac markers
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22
Q

abciximab is preferred for what kind of PCI reperfusion?

A

immediate

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23
Q

What 2 GP IIb/IIIa inhibitors are preferred for delayed PCI reperfusion?

A

tirofiban & eptifibatide

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24
Q

What GP IIb/IIIa requires renal dosing?

A

eptifibatide - administer 1 bolus & decrease infusion by 50%

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25
Q

GP IIb/IIIa inhib adverse effects

A
  • Thrombocytopenia

- Occult bleeding

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26
Q

abciximab description

A

GP IIb/IIIa inhibitor

Fab fragment of a humanized monoclonial antibody against GP IIb/IIIa receptor

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27
Q

tirofiban description

A

GP IIb/IIIa inhibitor

Nonpeptide, competitive inhibitor of the GP IIb/IIIa receptor

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28
Q

eptifibatide description

A

GP IIb/IIIa inhibitor

Cyclic peptide, competitive inhibitor of GP IIb/IIIa receptor

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29
Q

Unfractionated heparin MOA

A

Inhibits clotting factors IIa, IXa, Xa and XIIa (mostly IIa & Xa)

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30
Q

Unfractionated heparin general indications/dosing

A

UA/NSTEMI & STEMI treatment

DVT/PE prevention & treatment

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31
Q

Unfractionated heparin dosing in UA/NSTEMI w/o GPI

A

70 units/kg IV bolus followed by 15 units/kg/hr infusion

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32
Q

Unfractionated heparin dosing in UA/NSTEMI w/ GPI

A

60 units/kg IV bolus followed by 12 units/kg/hr infusion

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33
Q

Unfractionated heparin dosing in STEMI w/ GPI or fibrinolytic co-administered

A

60 units/kg IV bolus followed by 12 units/kg/hr infusion

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34
Q

Unfractionated heparin dosing in VTE prevention

A

5000 units SQ BID/TID

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35
Q

Unfractionated heparin in VTE treatment

A

80 units/kg IV bolus followed by 18 units/kg/hr infusion

36
Q

What parts of the CBC should you monitor when using Unfractionated heparin?

A

Hemoglobin, hematocrit & platelets

37
Q

What is the aPTT therapeutic goal in Unfractionated heparin therapy and how is it monitored?

A
  • aPTT therapeutic goal: 1.5-2.5x control

- monitor every 6hrs until 2 measurements are w/i therapeutic range, the every 24 while on therapy

38
Q

Dose adjustment for aPTT of <35 sec (1.2x control) in Unfractionated heparin therapy

A

Rebolus w/ 80 units/kg IV & increase infusion rate by 4 units/kg/hr

39
Q

Dose adjustment for aPTT 35-45 sec (1.2-1.5x control) in Unfractionated heparin therapy

A

Rebolus w/ 40 units/kg IV & increase infusion rate by 2 units/kg/hr

40
Q

Dose adjustment for aPTT of 46-70 sec (1.5-2.5x control) in Unfractionated heparin therapy

A

None

41
Q

Dose adjustment in aPTT of 71-90 sec (2.5-3.0x control) in Unfractionated heparin therapy

A

Decrease infusion rate by 2 units/kg/hr

42
Q

Dose adjustment for aPTT of >90 sec (>3.0x control) in Unfractionated heparin therapy

A

Stop infusion for 1 hr, then decrease rate by 3 units/kg/hr

43
Q

What is the reversal agent for UFH & what is the neutralization ratio?

A

IV protamine

1mg protamine neutralizes 100 units of UFH

44
Q

Thrombocytopenia is defined as a reduction in platelets below _____ or _____% from baseline.

A

<100,000 cells/uL or 50% fall from baseline

45
Q

How do you manage thrombocytopenia from UFH?

A

Change to non-heparin anticoagulant or hold all anticoags if under <50,000

46
Q

UFH cautions & contraindications

A
  • Hemorrhage (duh)
  • Malignant hypertension (stage III)
  • Thrombocytopenia (platelets <20,000)
  • Severel liver dz
47
Q

Low molecular weight heparin MOA

A

Inhibits factors Xa & IIA in a 4:1 ratio

48
Q

What is monitored in LMWH therapy?

A

CBC: H & H

49
Q

Why is anti-Xa level not monitored in LMWH therapy?

A

Anticoagulant response is very predictable

50
Q

Vitamin K antagonist MOA

A

Inhibits production of vitamin K dependent clotting factors II, VII, IX & X along with anticoagulant proteins C & S

51
Q

Why is there a delay in anticoagulant response to vitamin K antagonists?

A

Warfarin has NO impact on existing clotting factors and anticoagulant response is dependent on half-life of clotting factors

52
Q

How long does it take Warfarin to change coagulation properties? To become therapeutic?

A

2-4 days to change coagulation properties & > 1 wk to become therapeutic

53
Q

What is the usual starting dose of Vitamin K antagonists?

A

5-10mg PO QD

54
Q

What pts should have a reduced starting dose of vitamin K antagonists?

A

-Debilitated
-Malnourished
-CHF
- Liver dz
>60y

55
Q

How are vitamin K antagoinists abosrbed & metabolized?

A

Orally absorbed, 95% bound to albumin, metabolized in liver

56
Q

Which vitamin K antagonist isomer, R or S, is more active? What metabolizes them?

A

S is 5x more active than R & is metabolized by P450 2C; R is metabolized by P450 1A2/3A4

57
Q

What adverse effects are caused by vit K antagonists?

A
  • Purple toe syndrome

- Warfarin induced skin necrosis

58
Q

Vit K antagonist cautions

A
  • Hx of GI bleeding
  • recent neurosurgery
  • liver dz
  • heavy ETOH consumption
  • Non-compliant pts
  • high-risk fall pts
59
Q

Vit K contraindications

A
  • active bleeding (duh)
  • hemorrhagic tendicies (duh)
  • Pregnancy
  • hx of warfarin-induced skin necrosis
60
Q

How is warfarin monitored?

A

prothrombin time (PT)

61
Q

What does the PT measure?

A

The amount of time required for clot formation after Ca & thromboplastin are added to citrated plasma

62
Q

What is the INR?

A

International Normalized Ratio: attempts to standardize PT measurements using an international sensitivity index (ISI)

63
Q

What is the ISI and how does it fit into the INR equation?

A

ISI is a measure of thrompolastins responisiveness using a WHO reference:
(PT patient/PT control) ^ISI

64
Q

The INR goal and target range is 2.5 (2.0-3.0) except for:

A

Secondary prevention of AMI, prosthetic mechanical heart valve & pt w/ (+) ASA.

INR goal/range = 3.0 (2.5-3.5)

65
Q

How often do you monitor INR in hospitalized pts?

A

On 2nd day, then daily until in therapeutic range for 2 consecutive days

66
Q

How often do you monitor INR in outpatients?

A

2x in first week (day 3-4 & 5-7)
Once dose estab: INR every 1-2 weeks unit stabilized
Once stabilized: INR every 4-6 wks
Dose change: INR 1st wk, then every 1-2 wks, then every 4-6 wks

67
Q

Indirect factor Xa inhibitor MOA

A

Binds to antithrombin & selectively inhibits factor Xa using specific pentasaccharide sequence. Inhibits growth of formed thrombus and allows natural fibrinolytic system to degrade clot

68
Q

Direct factor Xa inhibitor MOA

A

Ribaroxaban selectively inhibits the active site of factor Xa, inhibits growth of formed thrombus & allows natural fibrinolytic system to degrade clot

69
Q

Indirect factor Xa inhibitor

A

fondaparinux (Arixtra)

70
Q

Direct factor Xa inhibitor

A

rivaroxaban (Xarelto)

71
Q

fondaparinux & rivaroxaban uses

A

VTE prevention after ortho surgery & treatment of DVT/PE

72
Q

What type of factor Xa inhibitors are indicated for afib?

A

direct

73
Q

Which 2 factor Xa inhibitors are cautioned in pts w/ renal insufficiency?

A

fondaparinux (Arixtra) & rivaroxaban (Xarelto)

74
Q

Which 2 factor Xa inhibitors are strong CYP 3A4 inhibitors/inducers?

A

rivaroxaban (Xarelto)
apixiban (Eliquis)

*don’t use rivaroxaban in severe hepatic failure

75
Q

What is unique about fondaparinux (Arixtra) administration compared to other factor Xa inhibitors?

A

It is administered SQ, whereas the others are all PO

76
Q

Direct thrombin inhibitor MOA

A

Binds directly and inhibits clotting factor IIa - does NOT require antithrombin. Can also inhibit clot-bound factor IIa

77
Q

What is the only direct thrombin inhibitor used for management of HIT?

A

argatroban

78
Q

What is bivalrudin commonly used for?

A

ACS w/ or w/o HIT

79
Q

What is dabigatran NOT used for and what are its only indications?

A

Not used for ACS

Only indicated for VTE treatment & afib

80
Q

Which direct thrombin inhibitor is monitored by aPTT?

A

argatroban

Monitor 2 hrs after start & 2 hrs after dose change

Goal: 1.5-2.5x control

81
Q

Which 2 direct thrombin inhibitors require renal function monitoring?

A

bivalirudin & dabigatran

82
Q

Which direct thrombin inhibitor requires hepatic enzyme monitoring?

A

argatroban

83
Q

Thrombolytic therapy MOA

A

Promotes conversion of plasminogen to plasmin resulting in thrombus breakdown

84
Q

Door-to-needle time must be _____ for thrombolytic therapy.

A

<30 mins

85
Q

Thrombolytics are indicated for a patient with:

A

ST segment elevation (>0.1 mV in 2 or more leads) presenting w/i 12 hr of symptom onset (ideal <3hr) & <75yo

PE leading to hemodynamic instability

DVT causing gangrene despite anticoagulation therapy