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PHCY310 Quiz am L47 Anticoagulation, erstellt von Mer Scott am 20/05/2019.

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L47 Anticoagulation

Frage 1 von 16

1

An overview of the clotting cascade:
1. Initiation:
Platelets adhere to vessel and more circulating platelets to . This provides a surface
where clotting factors assemble. Some clotting factors are . TF initiates coagulation. TF activates , forming Xa and IXa.
2. Amplification
IXa amplifies the activation of . The complex is a critical component, activating (thrombin)
3. Propagation
A burst of activated thrombin then converts , to form a mesh.

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    recruit
    aggregate
    released
    X and IX
    X
    FIIa
    Xa/Va
    fibrinogen to fibrin

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Frage 2 von 16

1

The clotting cascade has an " pathway" activated by trauma inside the vascular system. It is than the “extrinsic pathway”. The initiation involves XII, XI, IX, VIII.

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    intrinsic
    slower

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Frage 3 von 16

1

Warfarin is a Vitamin K “antagonist” that targets Vitamin K epoxide reductase in the liver.

Wähle eins der folgenden:

  • WAHR
  • FALSCH

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Frage 4 von 16

1

NOACs (novel oral anticoagulants) like dabigatran and rivaroxaban target thrombin and Xa.

Wähle eins der folgenden:

  • WAHR
  • FALSCH

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Frage 5 von 16

1

Choose the incorrect statement.

Wähle eine der folgenden:

  • It is a racemic mixture.

  • It is highly protein bound (>99%) and well absorbed.

  • It is renally metabolised.

  • S-warfarin has a greater clearance and shorter half life than R-warfarin.

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Frage 6 von 16

1

By inhibiting vitamin K epoxide reductase, warfarin increases the production of clotting factors II, VII, IX, X.

Wähle eins der folgenden:

  • WAHR
  • FALSCH

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Frage 7 von 16

1

The half-life of the FII is longer than warfarin and is the rate limiting step in the time course of the warfarin effect.

Wähle eins der folgenden:

  • WAHR
  • FALSCH

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Frage 8 von 16

1

Unfractionated heparin is found naturally in cells. It is a large with alternating disaccharide units of variable lengths.
- No anticoagulant activity
- Not available so given intravenously and subcutaneously
- Half-life of about hour
The antidote is a reversal agent called .
It binds to I, and induces a conformational change that enhances binding to clotting actors, helping to inhibit coagulation.

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    mast
    polymer
    intrinsic
    orally
    1
    protamine sulphate
    antithrombin II
    activated

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Frage 9 von 16

1

Low molecular weight heparins (LMWH)
• Given
• Enoxaparin halfe life ~
• Mainly -cleared
• Effect reversed by giving protamine sulphate
• Target is mostly anti-, some anti-IIa

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    subcutaneous
    5hrs
    renally
    partially
    Xa

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Frage 10 von 16

1

Novel oral anticoagulants (NOACs):
1. Dabigatran etexilate
• Competitive and reversible inhibition of free and clot bound
• Prodrug converted to active compound (dabigatran)
oral availability (~7%)
• ~80% cleared, ~20% glucuronidation
• Half life: ~12 hours
2. Rivaroxaban
• Competitive and reversible inhibition of free and clot bound
oral availability (>80%)
• ~35% renally cleared, ~65% (CYP3A4 and others)
• Half life: ~7-10 hours

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    thrombin
    Xa
    Low
    Good
    renally
    metabolised by liver

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Frage 11 von 16

1

PT, prothrombin time, is the time taken for plasma to clot in after the addition of . Normally it is 12-15 seconds. The PT ratio is the PT over the normal PT.
The International Normalised ratio (INR) is a “correction” of the PT ratio, or rather a correction of the large variability in the .
Low INR indicates a risk for while high INR indicates a risk for . The usual range is 2-3.

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    vitro
    TF & CaCl
    patient's
    average
    sensitivity of the reagents
    clotting
    bleeding

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Frage 12 von 16

1

Which of these is not a major determinant of warfarin dose requirements:

Wähle eine der folgenden:

  • Vitamin K status

  • Drug Interactions

  • Genetic differences (CYP2C9, VKORC1)

  • Age

  • Body size

  • Sex

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Frage 13 von 16

1

Most clinically important interactions with warfarin are well understood and can be predicted.
I.e these drugs:
• Inhibition of CYP2C9, e.g.
• Induction of CYPs, e.g.
• Inhibition if CYP3A4, 1A2 e.g.
Will affect the warfarin metabolism significantly.

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    amiodarone, fluconazole
    phenytoin, rifampin
    quinolones, macrolides, azoles

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Frage 14 von 16

1

Occasional consumption of vitamin K rich food is unlikely to be important in most patients but in the elderly and malnourished, vitamin K deficiency may increase risk of bleeding.

Wähle eins der folgenden:

  • WAHR
  • FALSCH

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Frage 15 von 16

1

Thrombolytic drugs (also called fibrinolytics) work by activating , to produce plasmin. breaks cross-links between molecules, disrupting the structural integrity of blood clots. They restore blood flow more than anticoagulants but carry a much higher of bleeding.

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    plasminogen
    Plasmin
    fibrin
    quickly
    risk

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Frage 16 von 16

1

t-PA binds to fibrin, converts plasmin to plasminogen, which digests fibrin.

Wähle eins der folgenden:

  • WAHR
  • FALSCH

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