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Regulation of Body Function > Anticoagulants > Flashcards

Anticoagulants Flashcards

1
Q

4 key antiplatelets

A

Aspirin
Clopidogrel
Ticagrelot
IIb/IIIa antagonists

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2
Q

2 key anticoagulants

A

Warfarin

Heparin (fractioned and unfractionated)

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3
Q

Anticoagulant indications

A 
Arterial disease
- CAD
- CVD
- PVD
Thromboembolic disease
- AF
- DVT/PE
- prosthetic cardiac valves
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4
Q

Vircow’s Triad

A

Hypercoagulability
Circulatory stasis
Vascular damage

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5
Q

Unfractionated heparin uses

A

Acute coronary syndromes
Thromboembolism (prophylaxis and treatment)
Temporary warfarin replacement (e.g., in pregnancy)

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6
Q

Unfractionated heparin mechanism of action

A

Binds to and increases activity of anti-thrombin III, which usually inactivates thrombin and Xa

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7
Q

How is unfractionated heparin given?

A

Intravenously or subcutaneously

No negative charge, therefore no GI absorption

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8
Q

Unfractionated heparin pharmacokinetics

A

Short half-life
Reticulo-endothelial uptake (rapid and easy to reverse)
Therefore rapid onset and offset of action
Variable bio-availability – unpredictable binding to cells and plasma proteins, therefore needs APTT monitoring

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9
Q

Adverse effects of unfractionated heparin

A

Bruising and bleeding, especially intracranial and gastrointestinal
Thrombocytopenia (heparin-induced thrombocytopenia) – autoimmune against platelets, can cause bleeding or clotting

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10
Q

Unfractionated heparin reversal

A

Stop heparin
Protamine
Monitor APTT

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11
Q

Protamine

A

Dissociates heparin from antithrombin III
Irreversible binding to heparin
Little effect on LMWH

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12
Q

LMWH mechanism of action

A

Bind to antithrombin III but do not inactivate thrombin, only affect factor Xa

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13
Q

Advantages of LMWH

A

Better absorbed therefore higher bioavailability and no need for IV
Longer half-life and more predictable dose-response
Lower risk of thrombocytopenia and bleeding

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14
Q

How id LMWH given?

A

Subcutaneously

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15
Q

Disadvantages of LMWH against UH

A

Cannot be monitored by APTT
Not fully reversible by protamine
Dose adjustment and reduction required in renal failure patients

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16
Q

LMWH uses

A

Non-STEMI/STEMI
DVT/PE
Warfarin alternative

17
Q

Warfarin mechanism of action

A

Antagonist of vitamin K which is a precursor to factors II, VII, IX and X
Slow onset of anticoagulation action

18
Q

Warfarin uses

A

Venous or arterial thrombosis treatment and prophylaxis

AF (to decrease risk of systemic emboli)

19
Q

Warfarin metabolism

A

S enantiomer metabolised by CYP450-2C9 which is affected by many other drugs and foods
R enantiomer metabolised by CYP450-1A2 and 3A4
Metabolised by glucuronidation and oxidation

20
Q

Oral warfarin

A

High bioavailability and rapid absorption

Long effective half life

21
Q

Warfarin adverse effects

A

Haemorrhage
Teratogenic – crosses placenta and uptaken into brain, bones and eyes
- last 4 weeks increased risk of intracranial haemorrhage

22
Q

Contraindications to warfarin therapy

A

Pregnancy
Uncontrolled alcohol/drug abuse
Dementia/psychosis
Fall risk

23
Q

INR

A

International normalised ratio

Patient’s PT in seconds/Mean normal PT in seconds

24
Q

Major drugs that potentiate warfarin (decrease CYP450-2C9)

A 
Alcohol (long-term)
Erythromycin (and others)
Omeprazole
Simvastatin
NSAIDs
and many more
25
Q

Major drugs that inhibit warfarin (increase CYP450-2C9)

A

Alcohol (short-term)
OCP
Barbiturates

26
Q

Prothrombinex

A

Prothrombin complex concentrate containing factor II, VII, IX, X and protein C
Given IV if severe bleeding occurring right now

27
Q

Hirudin

A

Uncommon thrombin inhibitor with little effect on platelets

Given IV

28
Q

Pentasaccharides

A

Uncommon
Indirect factor Xa inhibitor by promoting antithrombin–Xa complex
Given subcutaneously

29
Q

Rivaroxaban

A

Factor Xa inhibitor
Licensed for VTE and AF
Orally active

30
Q

Dabigatran

A

Dabigatran etexilate made into capsule with tartaric acid which increases absorption of drug across gut wall
Cleaved into dabigatran which is a competitive reversible inhibitor of thrombin
Not CYP dependent

31
Q

Dabigatran use

A

AF
VTE prevention and treatment
NOT mechanical valves

Regulation of Body Function (7 decks)

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