Mer Scott
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PHCY310 Quiz on L47 Anticoagulation, created by Mer Scott on 20/05/2019.

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L47 Anticoagulation

Question 1 of 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.

Drag and drop to complete the text.

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

Explanation

Question 2 of 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.

Drag and drop to complete the text.

    intrinsic
    slower

Explanation

Question 3 of 16

1

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

Select one of the following:

  • True
  • False

Explanation

Question 4 of 16

1

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

Select one of the following:

  • True
  • False

Explanation

Question 5 of 16

1

Choose the incorrect statement.

Select one of the following:

  • 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.

Explanation

Question 6 of 16

1

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

Select one of the following:

  • True
  • False

Explanation

Question 7 of 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.

Select one of the following:

  • True
  • False

Explanation

Question 8 of 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.

Drag and drop to complete the text.

    mast
    polymer
    intrinsic
    orally
    1
    protamine sulphate
    antithrombin II
    activated

Explanation

Question 9 of 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

Explanation

Question 10 of 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

Drag and drop to complete the text.

    thrombin
    Xa
    Low
    Good
    renally
    metabolised by liver

Explanation

Question 11 of 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.

Drag and drop to complete the text.

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

Explanation

Question 12 of 16

1

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

Select one of the following:

  • Vitamin K status

  • Drug Interactions

  • Genetic differences (CYP2C9, VKORC1)

  • Age

  • Body size

  • Sex

Explanation

Question 13 of 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.

Drag and drop to complete the text.

    amiodarone, fluconazole
    phenytoin, rifampin
    quinolones, macrolides, azoles

Explanation

Question 14 of 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.

Select one of the following:

  • True
  • False

Explanation

Question 15 of 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.

Drag and drop to complete the text.

    plasminogen
    Plasmin
    fibrin
    quickly
    risk

Explanation

Question 16 of 16

1

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

Select one of the following:

  • True
  • False

Explanation