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Pharmacology II - CP > Anticoagulants , Antiplatelets, Thrombolytics > Flashcards

Anticoagulants , Antiplatelets, Thrombolytics Flashcards

1
Q

anticoagulants definition

A

PREVENT clot formation or extension of existing clots

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2
Q

antiplatelets definition

A

reduce platelet aggregation on the surface of the platelet

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3
Q

thrombolytics definition

A

converts endogenous plasminogen to the fibrinolytic enzyme plasmin to dissolve newly formed blood clots

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4
Q

Four major counter regulatory pathways

A

fibrinolysis, tissue factor plasminogen inhibitor, protein c system, serine protease inhibitors

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5
Q

things that can prevent coagulation

A

endogenous anticoagulation factors, siliconized containers, heparin (CPB or dialysis), citrate ion

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6
Q

tissue factor plasminogen inhibitor action

A

inhibits extrinsic pathway by inhibiting TF-VIIa complex

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7
Q

coagulation propagation is inhibited by the

A

protein c pathway

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8
Q

4 key elements of the protein c pathway

A

protein c
thrombomodulin
endothelial protein c receptor
protein s

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9
Q

protein c

A

activated by thrombin to form activated protein c and inhibits activated factors V and VIII
is a potent anticoagulant, profibrinolytic, and anti-inflammatory

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10
Q

what is a cofactor to APC (activated protein C) in the inactivation of factor Va and VIIIa?

A

protein S

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11
Q

serpin/antithrombin

A

binds and inactivates thrombin, factor IIa, IXa, Xa, XIa, and XIIa

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12
Q

the enzymatic activity of antithrombin is enhanced

A

in the presence of heparin

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13
Q

any substance that deionizes the blood calcium will ___

A

prevent coagulation

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14
Q

____ charged citrate ion combines with ___ charged calcium in the blood to cause ___

A

negatively ; positively; unionized calcium compound

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15
Q

what can depress Calcium levels?

A

liver damage or massive transfusion where citrate ion can’t be removed quickly enough

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16
Q

Warfarin (coumadin) MOA

A

inhibits vitamin K resulting in defective factor II, VII, IX, X

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17
Q

what is coumadin contraindicated in?

A

pregnant women (crosses placenta)

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18
Q

what can we give to a parturient who has a clot?

A

heparin

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19
Q

coumadin pharmacokinetics

A

2.5-10mg dose varies depending on INR, onset 3-4 days, DOA 2-4 days

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20
Q

which processes have an INR goal of 2-3 on coumadin

A

afib, vte, pe, prevention of vte, tissue heart valves

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21
Q

which processes have an INR goal of 2.5-3.5 on coumadin?

A

mechanical heart valve, prevention of recurrent MI, history of vte

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22
Q

when to discontinue coumadin for minor surgery?

A

1-5 days for PT 20% within baseline

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23
Q

coumadin reversal with immediate surgery or active bleeding

A

vitamin k

2.5-20mg orally or 1-5 mg IV at rate of 1mg/min

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24
Q

emergency surgery coumadin reversal

A

FFP or 4-factor concentrate (Kcentra)

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25
Q

unfractionated heparin is ____ unpredictable than LMWH

A

more

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26
Q

heparin is a

A

naturally occurring polysaccharide that inhibits coagulation and enhances antithrombin

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27
Q

when unfractionated heparin binds to antithrombin it inactivates which coagulation enzymes?

A

thrombin IIa, factors IX, Xa, XI, XII

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28
Q

heparin must contain at least ____ units/mL

A

120 UPS

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29
Q

100 units/kg of heparin IV elimination half time

A

56 minutes

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30
Q

400 units/kg of Heparin IV elimination half time

A

152 minutes

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31
Q

a ____ in temperature prolongs the elimination half time of heparin

A

decrease

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32
Q

ACT monitoring with unfractionated heparin

A

get a baseline, 3-5 minutes post administration, then 30 minute - 1 hour intervals post administration

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33
Q

Clinical uses of unfractionated heparin

A

VTE SQ, PE prophylaxis, warfarin bridge, vascular or non-CPB (ACT 200-300s), interventional aneurysm clipping/coiling (>250s), CPB (>400-480s)

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34
Q

Dosing of unfractionated heparin for prophylaxis

A

5,000 units SQ q8-12h

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35
Q

Dosing of unfractionated heparin for treatment of thromboembolism

A

5,000 units IV, then continuous infusion for goal PTT 1.5-2.5 times control value

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36
Q

Dosing of unfractionated heparin for cardiopulmonary bypass

A

400 units/kg IV

37
Q

Dosing of unfractionated heparin for vascular interventions

A

100 - 150 units/kg IV

38
Q

Heparin side effects

A

hemorrhage, hematomas, thrombocytopenia (HIT), allergic reaction, hypotension, altered protein binding

39
Q

Considerations for IV heparin and neuraxial anesthesia

A

1 hour delay between needle placement and heparin admin
catheter should be removed 1 hour before heparin admin and 2-4 hours after last heparin dose
monitor PTT or ACT

40
Q

Mild or type I HIT

A

30-40% cases
non-immune mediated
plt count < 100,000
3-15 days after initiation of therapy

41
Q

Severe of type II HIT

A

immune mediated
plt count < 50,000
6-10 days after initiation of therapy

42
Q

patients with antithrombin deficiency will have a resistance to ____

A

heparin

43
Q

estrogen containing contraceptives decrease antithrombin’s ability to ____

A

inhibit Xa

44
Q

treatment for antithrombin deficiency with heparin resistance

A

2-4 units of FFP in adults

antithrombin concentrate

45
Q

heparin reversal

A

protamine

1 - 1.5 mg for each 100 units of heparin administered

46
Q

low molecular weight heparin differences from unfractionated heparin

A

less protein binding, elimination half life 24 hours, one daily dosing

47
Q

enoxaparin (lovenox) action

A

binds to and accelerates antithrombin

inhibits factor Xa and IIa so there is decreased thrombin activity and prevention of fibrin clot formation

48
Q

enoxaparin dose example for DVT prophylaxis

A

30 mg SQ every 12 hours

49
Q

advantages of LMWH/lovenox

A

reduced dosing frequency, more predictable, fewer effects on platelet function, reduced risk for HIT

50
Q

disadvantages of LMWH/lovenox

A

expensive, delay surgery for 12 hours after last dose, protamine not as effective in reversal

51
Q

What may be a better reversal for lovenox?

A

FFP

52
Q

advantages of direct oral anticoagulants

A

alternative to warfarin, rapid onset with peak effect in 2-4 hours, predictable, minimal drug interactions, no routine labs

53
Q

direct thrombin (IIa) inhibitor

A

dabigatran (pradaxa)

54
Q

Dabigatran (Pradaxa) pharmacokinetics

A

renal elimination
1/2 life = 12 hours
reversal: Idarucizumab (praxbind)

55
Q

Direct Factor Xa inhibitors

A

rivaroxaban (xarelto), apixaban (eliquis), edoxaban (savaysa)

56
Q

how are direct factor Xa inhibitors metabolized?

A

hepatic metabolism

57
Q

When to stop direct oral anticoagulants for low bleeding risk procedures?

A

24 hours prior

58
Q

When to stop direct oral anticoagulants for high bleeding risk procedures?

A

48 hours prior

59
Q

antiplatelet agents

A

cyclooxygenase inhibitors (ASA, NSAIDs), P2Y12 receptor antagonists, glycoprotein IIb/IIIa inhibitors

60
Q

antiplatelet MOA

A

suppress platelet function (inhibit platelet aggregation) for prevention of thrombosis

61
Q

Aspirin MOA

A

antithrombotic effects by inhibiting platelet aggregation, inhibits thromboxane A2 synthesis

IRREVERSIBLE, lasts life of a platelet

62
Q

Aspirin dosing

A

81-325 mg

63
Q

NSAIDs MOA

A

same as ASA except they reversibly depress thromboxane A2 production by platelets
often held prior to surgery

64
Q

primary prophylaxis should be ___ in perioperative period

A

continued but may be discontinued

65
Q

secondary prophylaxis should be ____ in perioperative period

A

continued

66
Q

Hold ASA in these circumstances:

A

intracranial, middle ear, posterior eye or intramedullary spine surgery, prostate surgery

67
Q

Clopidogrel MOA

A

P2Y12 - ADP receptor antagonist

pro-drug that is metabolized by CYP450 enzymes and inhibits platelet aggregation

68
Q

Ticagrelor

A

does not need hepatic activation

must be d/c’d 7 days prior to surgery

69
Q

What is useful in emergency surgery for someone who is taking clopidogrel or ticagrelor?

A

platelet transfusion

70
Q

indications for P2Y12 receptor antagonists

A

secondary prevention for MI, CVA, coronary artery stenting, acute coronary syndrome, peripheral artery disease

71
Q

withdrawal of ASA in patients with CAD is associated with

A

a 2-4 fold increase in death/MI

72
Q

patients with stents are at high risk of _____

A

thrombotic events especially in the first 3 months after insertion

73
Q

platelet glycoprotein IIb/IIIa antagonists MOA

A

act at fibrinogen receptors that are important for platelet aggregation
blocks fibrinogen

74
Q

platelet glycoprotein IIb/IIIa antagonists

A

abciximab (reopro), tirofiban (aggrastat), eptifibatide (integrilin)

75
Q

what ACT level do we want for people on platelet glycoprotein IIb/IIIa antagonists

A

between 200-400 seconds

76
Q

what are the 3 herbal agents that inhibit platelet aggregation?

A

garlic, ginkgo, ginseng

77
Q

how long should you discontinue garlic?

A

7 days

78
Q

how long should you discontinue ginkgo?

A

36 hours

79
Q

how long should you discontinue ginseng?

A

preferably 7 days but definitely 24 hours

80
Q

what else should does ginseng do besides inhibit platelet aggregation?

A

lowers blood glucose

81
Q

fibrin specific thrombolytics

A

alteplase, reteplase, tenecteplase

82
Q

non fibrin specific thrombolytic

A

streptokinase

83
Q

thrombolytics MOA

A

possess inherent fibrinolytic effects or enhances body’s fibrinolytic system by converting plasminogen to plasmin breaking down newly formed clots

84
Q

when are thrombolytics contraindicated?

A

trauma, severe HTN, active bleeding, pregnancy

85
Q

alteplase considerations

A

synthesized by endothelial cells
limited to use in first 3-6hours of ischemic stroke
short 1/2 life (5 minutes) - give as bolus then infusion

86
Q

thrombolytic efficacy

A

depends on the age of the clot

older clots have more cross linking and more compact = difficult to dissolve

87
Q

anticoagulants in general

A

delay or prevent clotting and have no effect after the clot is formed

88
Q

antithrombotics in general

A

influence the formation of clot by inhibiting platelet activity

Pharmacology II - CP (12 decks)

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