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Pharmacology-J > Anti-Thrombotics > Flashcards

Anti-Thrombotics Flashcards

1
Q

Importance of the GP IIb/IIIa conformation change

A

Allows receptors to bind to fibrinogen for aggregations

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2
Q

Biggest side effect of anti-thrombotics

A

Bleeding

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3
Q

Mechanism of ASA

A
  • COX inhibitor
  • Dec TxA2
  • Dec platelet activation
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4
Q

Therapeutic uses of ASA

A
  1. Atherothrombosis (primary and secondary prevention of ACS/CAD)
  2. Venous thromboembolism
  3. Colorectal cancer
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5
Q

Primary prevention

A

At risk

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6
Q

Secondary prevention

A

past medical history

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7
Q

Onset of ASA

A
  • Platelet inhibition <1 hour (<20 minutes if chewed)

- Delayed with enteric-coated tablets: 3-4 hours

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8
Q

Duration of ASA

A
  • Platelet inhibitory effect lasts entire platelet lifespan

- Rapid absorption in stomach and upper intestine

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9
Q

Metabolism of ASA

A
  • High first pass
  • Hydrolyzed to salicylic acid (inactive) by carboxylesterase-2 in GI mucosa, liver, synovial fluid, blood
  • half life of parent drug is 15 minutes; acetyl salicylate 3 hours
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10
Q

How is oral ASA effective if it has high first pass metabolism?

A

ASA comes into contact with 100% of blood supply in short period of time in portal system

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11
Q

How does ASA interact with NSAIDs?

A
  • NSAID is competitive w/ASA, prevents it from binding

- Give ASA first and wait about 2 hours to give ibuprofen

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12
Q

Inhibition of ___ of the capacity of the platelets to generate TxA2 is necessary to inhibit platelet function

A

> 95-98%

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13
Q

Contraindication to ASA

A
  • TRUE hypersensitivity
  • Active bleeding
  • Severe bleeding risk
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14
Q

Side effects of ASA

A
  • GI (dyspepsia, erosive gastritis, peptic ulcers)
  • Prostaglandin depletion causing topical injury to mucosa
  • Increases risk of hemorrhagic stroke in men by a factor of 1.7
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15
Q

P2Y12 ADP inhibitor drugs

A
  • Clopidogrel (Plavix)
  • Prasugrel
  • Ticagrelor
  • Cangrelor
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16
Q

Mechanism of P2Y12 inhibitors

A

Inhibits P2Y12 receptor from releasing granules, which prevents activation of GPIIb/IIIa and inhibits platelet aggregation

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17
Q

Pharmacologic class of clopidogrel

A

Thienopyridine

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18
Q

Is plavix reversible or irreversible?

A

Irreversible receptor blockade

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19
Q

Administration of clopidogrel

A

Oral

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20
Q

Frequency of clopidogrel dose

A

Once a day, but requires loading dose

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21
Q

Is clopidogrel a prodrug?

A

Yes

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22
Q

Onset of action of Plavix

A

2-8 hours, max effect 15-24 hours

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23
Q

Offset of action of Plavix

A

7-10 days

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24
Q

CYP drug interactions of plavix

A

CYP2C19

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25
Q

Why is Ticlopidine never used?

A

Causes diarrhea, rashes, neutropenia, thrombotic thrombocytopenic purpura

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26
Q

What percentage of clopidogrel is an inactive metabolite?

A

85%

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27
Q

Would a drug that inhibits CYP2C19 amplify or reduce clopidogrel antiplatelet effect?

A

Reduce

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28
Q

True/false: poor metabolizers of clopidogrel means clopidogrel as a preventative therapy is reduced

A

True

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29
Q

Clopidogrel clinical uses

A
  • ACS +/- PCI (percutaneous coronary intervention)
  • Dual antiplatelet therapy
  • CAD, CVD and/or PAD comparable to ASA in secondary prevention of atherothrombotic disease
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30
Q

Onset of action of Prasugrel

A

30 min-4hrs

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31
Q

CYP drug interaction of prasugrel

A

None

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32
Q

Faster onset of action and more potent platelet inhibition than clopidogrel

A

Prasugrel and Ticagrelor

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33
Q

Contraindications to Prasugrel

A
  • Patients <60 kg (half dose recommended)
  • hx stroke/TIA
  • pts >75 y/o (unless high-risk ischemic features such as DM)
  • Pts who do NOT undergo revascularization/PCI (due to inc in CABG related bleeding)
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34
Q

Pharmacologic class of Ticagrelor

A

CPTP

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35
Q

Receptor blockade of Ticagrelor

A

Reversible receptor blockade

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36
Q

Frequency of Ticagrelor

A

BID

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37
Q

Is Ticagrelor a prodrug?

A

No, it’s active right away

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38
Q

Onset of action of Ticagrelor

A

30 min-4 hrs

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39
Q

Offset of action of Ticagrelor

A

3-5 days

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40
Q

CYP drug interaction of Ticagrelor

A

CYP3A

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41
Q

Difference between Ticagrelor active metabolite and others

A

Ticagreor AM has a longer half life, but is otherwise the same

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42
Q

Why does Ticagrelor cause a sensation of dyspnea

A
  • P2Y12 inhibitors increases neuronal signaling, increasing conductivity of pulmonary vagal C-fibers
  • Because Ticagrelor is BID, the second dose binds to the newly created receptors
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43
Q

Pharmacologic class of cangrelor

A

ATP analogue

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44
Q

Receptor blockade of Cangrelor

A

Reversible

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45
Q

Administration route of Cangrelor

A

IV

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46
Q

Frequency of Cangrelor

A

Bolus plus infusion

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47
Q

Is Cangrelor a prodrug?

48
Q

Onset of action of cangrelor

49
Q

Offset of action of cangrelor

50
Q

CYP drug interaction of Cangrelor

51
Q

Indications for cangrelor

A

P2Y12 receptor inhibitor-naive patients undergoing PCI

52
Q

True/false cangrelor has higher bleeding rates than clopidogrel

53
Q

Causes dyspnea sensation

A

Ticagrelor and Cangrelor

54
Q

Mechanism of Cilostazol

A
  • Phosphodiesterase 3 inhibitor (inc cAMP levels, reduces Ca++, inhibits platelets
  • Inhibits vascular smooth muscle cell proliferation
  • Improves peripheral blood flow
55
Q

Indications of cilostazol

A
  • FDA: PAD (increases exercise tolerance)
  • stroke/TIA
  • Post-PCI
  • PVD
56
Q

Contraindications of cilostazol

A

Heart failure

57
Q

Mechanism of vorapaxar

A
  • Blocks the platelet thrombin receptor (PAR-1)

- inhibits thormbin induced platelet aggregation

58
Q

Indications for vorapaxar

A

-Post MI patients at risk for secondary atherothrombotic events (initiated in stable patients >2 weeks after an MI on antiplatelet therapy

59
Q

Contraindications for vorapaxar

A
  • first time in patients presenting with ACS

- Hx stroke, TIA, ICH, active pathological bleeding

60
Q

Use vorapaxar with caution in patients with:

A
  • low body weight (<60kg)
  • older age
  • hx bleeding diathesis
61
Q

Half life of vorapaxar

62
Q

Vorapaxar is eliminated by

A

Metabolism by CYP3A

-Avoid use with strong CYP3A4 inhibitors

63
Q

GP IIb/IIIa inhibitor mechanism of action

A

-Prevents platelet aggregation

64
Q

Administration of GP IIb/IIIa inhibitors

A

-IV or intra-coronary

65
Q

Indications for GPIIb/IIIa inhibitors

66
Q

Onset of action for GP IIb/IIIa inhibitors

67
Q

Potent platelet inhibition

A

GPIIb/IIIa inhibitors

68
Q

GP IIb/IIIa inhibitor drugs

A
  • Abciximab
  • Eptifibatide
  • Tirofiban
69
Q

Contraindications of GP IIb/IIIa inhibitors

A
  • Active or recent bleeding (4-6 weeks)
  • Severe hypertension (?180-200/110)
  • Any hemorrhagic CVA or CVA within 30 days-2 years
  • Major surgery or trauma within 4-6 weeks
  • Thrombocytopenia
  • Bleeding diathesis/warfarin with elevated INR
70
Q

Abciximab characteristics

A
  • Fab fragment of humanized mouse monoclonal antibody
  • Not specific for GP IIb/IIIa
  • Plasma half life is short
  • Platelet bound half life is long
  • No renal clearance
71
Q

Eptifibatide characteristics

A
  • Cyclical KGD-containing heptapeptide
  • Specific for GP IIb/IIIa
  • Long plasma half life
  • Short platelet bound half life
  • Renal clearance
72
Q

Tirofiban characteristics

A
  • Nonpeptidic RGD-mimetic
  • Specific for GPIIb/IIIa
  • Long plasma half life
  • Short platelet bound half life
  • Renal clearance
73
Q

Parenteral Anticoagulant drugs

A
  • Unfractioned Heparin
  • Low molecular weight heparins
  • Synthetic pentasaccharides
  • Direct thrombin inhibitors
74
Q

Uses for parenteral anticoagulants

A
  • treatment and prophylaxis of venous thrombosis and pulmonary embolism
  • initial management of ACS
75
Q

Mechanism of parenteral anticoagulants

A
  • Induce a conformational change in antithrombin that accelerates its interaction with clotting factors
  • To inhibit thrombin, heparin must bind to both the coagulation enzyme and AT
  • only heparin chains >18 saccharide units are of sufficient length to bind thrombin
  • Small heparin fragments catalyze inhibition of factor Xa by antithrombin
76
Q

Heparin administration

A

IV or subcutaneous

77
Q

Heparin mechanism of action

A
  • Heparin interacts with antithrombin to change its conformation and enhance its ability to
    inactivate clotting factor proteases, especially thrombin (IIa), IXa and Xa
78
Q

Heparin metabolism

A

Cleared and degraded by the reticuloendothelial system (dose-dependent clearance)

79
Q

Heparin reversal

A

Protamine sulfate

80
Q

Protamine sulfate mechanism of action

A

Acts as heparin antagonist by complexing with the strongly acidic heparin to form a stable complex devoid of anticoagulation action

81
Q

Onset of protamine sulfate

82
Q

Dosing of protamine sulfate

A

1mg for 100 units of heparin to neutralize, but no faster than 50mg/10min

83
Q

Triggered by antibodies directed against neoantigens of PF4

Binding activates platelets and generates prothromotic platelet microparticles, promoting thrombin generation

A

Heparin-Induced Thrombocytopenia

84
Q

Low molecular weight heparin characteristics

A
  • mean MW 4500-5000 d
  • <18 saccharide units are unable to bind simultaneously to ATIII and IIa and are unable to accelerate thrombin inactivation by ATIII
  • LMWH catalyzes inhibition of Xa by ATIII
  • Anti-Xa: IIa ratio of 2-4:1
85
Q

LMWH drugs

A
  • Enoxaparin (Lovenox)
  • dalteparin (fragmin)
  • tinzaparin (innohep)
86
Q

Pharmacokinetics of LMWH

A
  • subcutaneous with 91% bioavailability
  • Less binding to endothelial cells, macrophages, heparin-binding plasma proteins
  • longer half life
  • minimal need for monitoring
  • cleared renally
  • lower risk HIT
  • partially reversed by protamine
87
Q

LMWH uses

A
  • DVT prophylaxis
  • Surgery, abdominal, hip/knee replacement
  • Medical patients with severe mobility restrictions
  • Acute DVT or PE
  • ACS
88
Q

LMWH boxed warning

A

Epidural or spinal hematomas may occur

89
Q

Synthetic pentasaccharide drug

A

Fondaparinux (arixtra)

90
Q

Pharmacokinetics of fondaparinux

A
  • SubQ bioavailability is 100%
  • Half life 17-21 hours (dose Q24hr)
  • major bleeding in 2-3%
  • thrombocytopenia in 2.9%
  • No HIT risk
  • do not use if CrCl 30ml/min
  • black box warning for spinal or epidural hematomas
91
Q

Agratroban characteristics

A
  • Treatment for HIT
  • Metabolized by hepatic CYPs & excreted in bile
  • Continuous IV infusion
  • Plasma half life 45 min
  • Monitoring goal: aPTT 1.5-3x baseline
  • Prolongs INR
92
Q

Direct thrombin inhibitor drugs

A
  • Agratroban

- Bivalirudin

93
Q

Bivalirudin characteristics

A
  • Bivalent
  • IV infusion as alternative to heparin in pts undergoing PCI
  • plasma half life of 25 minutes
  • degraded by peptidases & partially excreted by kidneys
94
Q

Oral anticoagulants

A
  • Warfarin
  • Direct thrombin inhibitor (dabigatran)
  • Factor Xa inhibitors (rivaroxaban, apixaban, edoxaban)
95
Q

Oral anticoagulants

A
  • Warfarin
  • Direct thrombin inhibitor (dabigatran)
  • Factor Xa inhibitors (rivaroxaban, apixaban, edoxaban)
96
Q

Common clinical uses for oral anticoagulants

A
  • Treatment and prophylaxis of venous thromboembolism and pulmonary embolism
  • Prevention of stroke and venous thromboembolism in patients with afib
97
Q

Warfarin mechanism

A

interferes with the synthesis of vitamin K dependent clotting factors (II, VII, IX, X)

98
Q

Warfarin characteristics

A
  • Anticoagulant effect is observed after elimination of normal preformed clotting factors 48-72 hours after administration
  • Recovery requires the synthesis of new normal clotting factors
99
Q

INR for patients on warfarin

A
  • 2.0-3.0 is recommended to balance safety and efficacy for most patients
  • You want to be in this range 66% of the time
100
Q

Factors that correlate with warfarin dose

A
  • Age
  • Body surface area/weight
  • amiodarone
  • acetaminophen
  • race
  • sex
  • plasma vitamin K level
  • decompensated CHF
  • chemotherapy
  • genetic status
101
Q

Adverse effects of warfarin

A
  • bleeding

- skin necrosis (3-10 days after initiation, widespread thrombosis, protein C depletion -leads to coagulation

102
Q

Potential warfarin reversal

A
  • Recombinant factor VIIa (immediate)
  • PCC (immediate)
  • fresh frozen plasma (immediate)
  • IV vitamin K (8-12 hours)
  • Oral vitamin K (24 hours)
103
Q

Direct oral anticoagulant drugs

A
  • Dabigatran
  • Rivaroxaban
  • Apixaban
  • Edoxaban
104
Q

Direct oral anticoagulant drug characteristics compared to warfarin

A
  • Rapid onset
  • Fixed dosing
  • No food effect
  • Few drug interactions
  • No monitoring
  • No antidote
105
Q

Dabigatran characteristics

A
  • Factor IIa target (thrombin)
  • prodrug
  • 3-7% bioavailability
  • 1-3 hrs to cmax
  • 12-17 hr half life
  • 80% renal clearance
  • 5-10% dyspepsia
106
Q

Rivaroxaban characteristics

A
  • Factor Xa target
  • 66% bioavailability (100% w/food)
  • 2-4hrs to cmax
  • 5-13 hr half life
  • 33% renal clearance
  • CYP3A4 elimination
  • absorbs w/food
107
Q

Apixaban characteristics

A
  • Factor Xa target
  • 50% bioavailabiity
  • 3-4 hours to cmax
  • 9-14 hr half life
  • 27% renal clearance
  • Minor CYP3A4 elimination
108
Q

Edoxaban characteristics

A
  • Factor Xa target
  • 62% bioavailability
  • 1-2 hrs to cmax
  • 10-14 hr half life
  • 50% renal clearance
  • minimal CYP3A4 metabolism
  • absorbs w/food
109
Q

Boxed warning for factor Xa inhibitors

A
  • Place pts at increased risk of thrombotic events

- inc risk of stroke with discontinuing meds w/nonvalvular afib

110
Q

DOAC antidotes

A
  • Idarucizumab (monoclonal antibody for dabigatran)

- Andexanet alfa (inactivated factor Xa for factor Xa inhibitors)

111
Q

Thrombolytic drugs

A

Streptokinase

112
Q

Streptokinase mechanism of action

A
  • bind to fibrin on the surface of the clot
  • activates fibrin-bound plasminogen
  • plasmin cleaved from plasminogen associated with the fibrin
  • fibrin molecules are broken apart by the plasmin and the clot dissolves
113
Q

Thrombolytics indications

A
  • STEMI
  • DVT
  • PE
  • acute ischemic stroke
  • acute peripheral arterial occlusion
114
Q

Thrombolytic adverse reactions

A
  • ICH

- Other serious bleeding <5%

115
Q

Absolute contraindications to thrombolysis

A
  • prior ICH
  • known cerebral vascular leasion
  • known malignant intracranial neoplasm
  • ischemic stroke within 3 mos except acute ischemic stroke w/in 3 hours
  • suspected aortic dissection
  • active bleeding
  • significant closed head or facial trauma within 3 mos
116
Q

Relative contraindications to thrombolysis

A
  • Hx chronic or severe poorly controlled HTN (and acute)
  • Hx prior ischemic stroke >3 mos, dementia or known intracranial pathology
  • Traumatic or prolonged (>10 min) CPR or major surgery (<3 wks)
  • Recent (w/in24hrs) internal bleeding
  • noncompressible vascular punctures
  • pregnancy
  • active peptic ulcer
  • current use of anticoagulants

Pharmacology-J (3 decks)

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