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Y2 Pharmaco > Anti-thrombotic Agents (antiplatelets) > Flashcards

Anti-thrombotic Agents (antiplatelets) Flashcards

1
Q

Name the 3 types of anti-clotting drugs:

A
  1. Anti-platelet
  2. Anti-coagulants
  3. Thrombolytics/Fibrinolytics
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2
Q

What kind of anti-clotting drug is aspirin?

A

Anti-platelet drug

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3
Q

What kind of anti-clotting drug is clopidogrel?

A

Anti-platelet drug

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4
Q

What kind of anti-clotting drug is Abciximab?

A

Anti-platelet drug

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5
Q

What kind of drugs are heparin and warfarin?

A

Anti-coagulants

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6
Q

Haemostasis process:

A
  1. Vasoconstriction/ vascular spasm
  2. Platelet adhesion, activation, aggregation
  3. Fibrin formation
  4. Network of fibrin
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7
Q

What is the lifespan of a platelet?

A

7-10days

  • so inhibitory effect of aspirin which lasts for life of platelet also lasts for 7-10 days
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8
Q

Adverse effects of anti-thrombotics, anti-platelets:

A
  1. Bleeding (PGI2)
  2. Gastric upset & ulcers (PGE2)
    - GIT bleeding
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9
Q

Clinical uses of Aspirin:

A

Prevention of arterial thrombosis (e.g. myocardial infarction, stroke)
- prophylactic treatment of transient cerebral ischemia
- reduce incidence of recurrent MI
- decrease mortality in postmyocardial infarction patients

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10
Q

What allows the cross-linking of fibrinogen?

A

GP IIB/IIA (glycoprotein 2B 3A)
- platelet membrane surface protein
- which allows fibrinogen cross-linking of platelets

Pg 7 of slides

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11
Q

How is heparin delivered?

A
  • intravenously or subcutaneously
  • CANNOT be given intramuscularly (will form haematomas!)
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12
Q

Adverse effects of heparin:

A
  1. Haemorrhage
    - to stop heparin therapy + start on treatment w protamin sulfate
    - protamin sulfare binds to heparin due to opposite charge -> isolates heparin
  2. Thrombosis & thrombocytopenia
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13
Q

Which anti-thrombotic drug is not contraindicated in pregnancy?

A

Heparin
(Only antithrombotic drug in pregnancy)

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14
Q

MOA of Aspirin as an anti-platelet?

A
  1. Irreversible COX inhibitor
  2. Inhibits TXA2 synthesis in platelets => inhibits platelet aggregation
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15
Q

MOA of Clopidogrel?

A
  1. Pro-drug: converted to active metabolite by CYP2C19
  2. P2Y 12 receptor irreversible antagonist => inhibit ADP-induced platelet aggregation
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16
Q

MOA of Abcimiximab:

A

Abcimiximab: Fibrinogen Receptor Antagonist

  1. Humanised Fab (antigen-binding fragment) mAb
  2. Fibrinogen receptor antagonist => inhibit platelet aggregation
17
Q

Name the newer P2Y 12 receptor antagonists:

A
  1. Prasugrel: pro-drug, irreversible, fast onset
  2. Ticagrelor: direct, reversible
18
Q

MOA of Unfractionated Heparin (UFH)

A
  • anticoagulant
  1. Binds & activates AT-III (plasma protease inhibitor)
  2. Enhance AT-III interaction w clotting factors (IIa, IXa, Xa) by 1000 folds => form inactive complexes
  3. Conformational change of AT-II
  4. Stimulate TFPI release from endothelium
19
Q

MOA of Low-MW Heparin (LWMH)

A

Anticoagulant

  1. Bind & activate AT-III
  2. Inhibit Factor Xa more, Factor IIa less
    - fractionation of UFH
    - more homogenous than UFH
20
Q

MOA of Vitamin K Antagonist - Warfarin

A
  1. Inhibit Vit K Epoxide Reductase => decreased Vit K formation
  2. Decreases Vit K co-factor for activation of Factors II, VII, IX, X by γ-Caboxylase
    - racemic mixture of equal amounts of optical isomers
    -> S-warfarin: 4x more potent
    -> R-warfarin
21
Q

MOA of Direct Anticoagulants - Rivaroxaban, Dabigatran

A
  1. Rivaroxaban : Factor Xa inhibitor
  2. Dabigatran: Thrombin IIa inhibitor
22
Q

List the 4 types of Anticoagulants:

A
  1. Unfractionated Heparin (UFH)
  2. Low-MW Heparin (LWMH)
  3. Vitamin K Antagonist (Warfarin)
  4. Direct Anticoagulants (Rivaroxaban, Dabigatran)
23
Q

Which Anticoagulant cannot be given during pregnancy?

A

Warfarin.
- crosses placenta
- Teratogen => can cause Fetal Warfarin syndrome, birth defects, haemorrhagic foetus, abortion

24
Q

What is a Teratogen?

A
  • substance that interferes with normal fetal development and causes congenital disabilities.
25
Q

What are the adverse effects of Warfarin?

A
  1. Narrow therapeutic window
  2. Bleeding
  3. Teratogen
    - fetal warfarin syndrome, birth defects, haemorrhagic foetus, abortion
  4. Rare effects
    - cuteneous necrosis * infarction of boob, butt, intestine, extremities
26
Q

MOA of fibrinolytics?

A

Converts plasminogen to plasmin => plasmin lyses clot

27
Q

Name the antidotes for overdose of anticoagulants..

A
  1. Discontinuance
  2. Heparin antidote: Protamine Sulfate
  3. Warfarin antidote: ** Vitamin K1 (Phytonadiona)**
28
Q

Antidote for heparin:

A

Protamine Sulfate
- highly basic peptide => forms stable complex w Heparin

29
Q

Antidote for Warfarin

A

Phytonadione, Vitamin K1
- replenish Vit K => re-establish normal activity of clotting factors

30
Q

Name the 3 Fibrinolytics..

A
  1. Streptokinase
  2. Urokinase
  3. Tissue Plasminogen Activator (t-PA)

Y2 Pharmaco (22 decks)

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