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PR3154 > pre-IC3 > Flashcards

pre-IC3 Flashcards

1
Q

How do anti-platelets work?

A

Block platelet aggregation & primary haemostasis

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2
Q

4 key steps in haemostasis & thrombosis

A
  1. Vasoconstriction
  2. Primary haemostasis (recruitment of platelets & clotting factors)
  3. Secondary haemostasis (thrombin activation & fibrin polymerisation)
  4. Clot stabilisation
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3
Q

How do anti-coagulants work?

A

Block activation of fibrin polymerisation & secondary haemostasis

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4
Q

When does extrinsic pathway occur

A

Tissue damage

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5
Q

When does intrinsic pathway occur

A

Surface contact (e.g. with glass, collagen, or subendothelium)

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6
Q

MOA for warfarin

A

Vit K antagonist; Inhibits vitamin K reductase enzyme that reactivates oxidised vitamin K

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7
Q

Should vit K be active or inactive to achieve anti-coagulation? Hence should it be reduced or oxidised form?

A

Inactive form (oxidised); because the active form drives activation of clotting factors

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8
Q

Warfarin is primarily metabolised in the liver by _______

A

CYP2C9

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9
Q

What causes variability in warfarin response?

A

Genetic polymorphisms in CYP2C9 and vit K reductase complex subunit 1 (VKORC1)

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10
Q

Adverse effects of warfarin

A
  • Haemorrhage/ bleeding
  • Hepatitis
  • Cutaneous necrosis
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11
Q

Contraindication for warfarin

A
  • Active bleeding
  • Severe or malignant HTN
  • Severe renal/ hepatic disease
  • Pregnancy
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12
Q

Reversal agent for warfarin

A

Vit K

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13
Q

Reversal agent for dabigatran

A

Idacizumab

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14
Q

MOA for dabigatran

A

Antagonist of thrombin (factor IIa)
*Competitive & reversible

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15
Q

MOA for rivaroxaban

A

Antagonist of activated factor Xa; competitive & reversible

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16
Q

Reversal agent for rivaroxaban & how it works

A

Andexanet alfa; acts as recombinant factor Xa

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17
Q

Which drug reduce dabigatran level?

A

Rifampin

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18
Q

Which kind of drug reduce rivaroxaban level?

A

P-glycoptn & CYP3A4 inducers

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19
Q

Adverse effects: rivaroxaban

A

bleeding

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20
Q

Adverse effects: dabigatran

A

bleeding, GI symptoms

21
Q

Example of LMWH

A

Enoxaparin

22
Q

LMWH is more selective for factor ______ than ____

A

Xa; IIa

23
Q

MOA for heparin

A

Active heparin binds to anti-thrombin III -> inactivates thrombin (factor IIa) and factor Xa

24
Q

Which factor is thrombin?

A

factor IIa

25
Q

Reversal agent for heparin

A

Protamine sulfate (derived from salmon sperm)

26
Q

Reversal agent for LMWH

A

Protamine sulfate (but not complete reversal)

27
Q

Can heparin/ LMWH be used in pregnancy?

A

Yes

28
Q

Why is LMWH preferred over heparin?

A
  • Longer t1/2
  • Higher bioavailability
  • Lower risk of thrombocytopenia
29
Q

How does heparin induce thrombocytopenia?

A
  1. Heparin binds to platelet factor 4 (PF4) on activated platelet surface
  2. IgG antibody is produced against heparin-PF4 complex
30
Q

MOA for dipyridamole

A

Adenosine reuptake & PDE3 inhibitor -> incr cAMP within platelets -> inhibits platelet activation & aggregation

31
Q

What kind of preparation is dipyridamole often given as?

A

Modified-release preparation

32
Q

Adverse effects: dipyridamole

A
  • Headache
  • Hypotension
33
Q

When to avoid dipyridamole

A

Hypotension/ severe coronary artery disease

34
Q

MOA of aspirin

A

Irreversible COX inhibitor (COX-1 > COX-2) -> inhibits platelet production of thromboxane A2

35
Q

Examples of antiplatelets

A
  • Dipyridamole
  • Aspirin
  • Clopidogrel, Ticagrelor
36
Q

Is aspirin more effective at high/ low dose as an antiplatelet?

A

Low dose

37
Q

Adverse effects: aspirin

A
  • Upper GI events e.g. gastric ulcer, bleeding
  • Incr risk of bruising/ bleeding
38
Q

Variation in onset of clopidogrel action is due to ____

A

CYP2C19-mediated metabolism of clopidogrel (prodrug) into active form

39
Q

MOA: clopidogrel / ticagrelor

A

P2Y12 inhibitor -> prevents activation of glycoptn receptors -> prevents platelet recruitment & aggregation

40
Q

Clopidogrel: Irreversible or reversible P2Y12 inhibitor?

A

Irreversible

41
Q

Ticagrelor: Irreversible or reversible P2Y12 inhibitor?

A

Reversible

42
Q

Adverse effects: Clopidogrel/ ticagrelor

A
  • Bleeding (incl intracranial bleeding)
  • Easy bruising
  • Dyspepsia
  • Rashes
  • Bronchospasm
  • Dyspnea
  • Hypotension
43
Q

Adverse effects: ticagrelor

A
  • Bleeding (incl intracranial bleeding)
  • Easy bruising
  • Bradycardia
  • Cough
44
Q

Role of fibrinolytic (thrombolytic)

A

Breaks down fibrin crosslinking to reverse clot stabilisation

45
Q

MOA: alteplase

A

Recombinant tissue-type plasminogen activators (t-PA); binds preferentially to clot-associated plasminogen, activating plasmin at the clot -> fibrinolysis

46
Q

Adverse effects: alteplase

A
  • Haemorrhage/bleeding
  • Ventricular arrhythmias, hypotension, oedema
  • Cholesterol embolization, venous thromboembolism
  • Hypersensitivity and anaphylaxis
47
Q

Reversal agents for fibrinolytics and how they work

A

Tranexamic acid / aminocaproic acid;

Compete for lysine binding sites on plasminogen and plasmin-> block fibrinolytic’s interaction with fibrin

48
Q

Which drug reduces alteplase level?

A

Nitroglycerin

PR3154 (19 decks)

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