Antithrombotic Drugs Flashcards

1
Q

How are anticoagulants given; the predominant way and other ways

A

Direct Oral Anticoagulants (DOACs) 90%

Also orally and heparin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the name + role of a predominant oral anticoagulant

A

Prevents unwanted thrombosis

Warfarin - Vitamin K Antagonist

(Wisconsin Alumni Research Foundation -arin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Mechanism of Warfarin

A

Vitamin K normally supports production of prothrombin and coagulation factors as it is involved in post-ribosomal carboxylation of their glu acid residues, needed to function

warfarin blocks Vit K reductase, needed for Vit K to act as a co-factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What can warfarin be used for

A

Patients with replaced heart valves
Atrial Fibrillation
Pulmonary Embolism
DVT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the time frame for warfarin to act (Broadly)

A

Several days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How is warfarin’s therapeutic window found

A

Patient’s INR (prothrombin time) is measured; target dose adjusted accordingly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What must be kept in mind during warfarin prescription

A

Drug interactions and Side Effects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Main side effect of warfarin

A

Bleeding as a result of lack of coagulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are some injectable anticoagulants

A

Unfractionated heparin or LMWHs [Low molecular weight heparin] (e.g. enoxaparin, tinzaparin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Mechanism of injectable anticoagulants

A

Activating antithrombin III; antithrombin inactivates some clotting factors and thrombin by complexing with serine protease of some coagulation factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Discuss the time frame of heparin to kick in

A

Immediate action (used whilst warfarin takes effect)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Direct Oral Anticoagulants (DOAC)

A

Like warfarin but:
Far less interactions
Less bleeding than warfarin
Does not require monitoring

Rapid

Mechanisms such as acting as thrombin inhibitors or activated factor X inhibitors

Seemingly equally effective as warfarin in treating AF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the benefit of Warfarin over DOACs

A

DOACs cannot be easily reversed (until recently; done with mAB which can reverse it) while warfarin can just be reversed using Vit K

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

DOACs vs Warfarin in principle

A

DOACs act directly on the coagulation cascade while warfarin acts on the factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Prostacyclin

A

A member of the prostaglandin group of lipid molecules made in epithelia of blood vessel walls

It is a vasodilator and anti-platelet agent; increases cAMP

(PGI2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Thromboxane

A

Txa2

Released by platelets when platelets adhere, causing further adhesion and decrease of cAMP

17
Q

Nitric Oxide in Blood

A

Blood vessels release NO to keep blood pressure down;

it also prevents both platelet adhesion and aggregation through increasing platelet cGMP

18
Q

Aspirin

A

Low dose anti platelet drug

Used to proevent MI in patients who have previously had an MI;

Inhibits cyclooxygenase

19
Q

Mechanism of Aspirin

A

Aspirin irreversibly inhibits cyclo-oxygenase, reducing thromboxane

20
Q

Why does aspirin greatly favour PGI2 production over TXA2

A

Patient takes aspirin; it hits both enzymes

Endothelia are nucleated though, which produce more mRNA, so they can re-produce COX within 2 hours
Platelets are anuclear, so they cannot produce COX and thus thromboxane (for 7 days till new ones are synthesised)

21
Q

Clopidogrel

A

Drug that inhibits ADP binding to the receptors, reducing expression of glycoprotein IIb/IIIa

Good in blocking cerebrovascular disease

(Think of it in the class of an ADP blocker)

22
Q

Abciximab

A

Monoclonal Antibody that binds to glycoprotein IIb/IIIa, inhibting its actions, given to patients undergoing angioplasty; only use once

23
Q

Thrombolytics

A

Used in breakdown of clots

Alteplase

Dissolves clot and restores blood flow

Primary treatment of stroke and pulmonary embolism

24
Q

What has replaced the use of thrombolytics in myocardial infarctions

A

Angioplasties with a stent

25
Q

Contra-indications of Alteplase

A

Hemmoragic strokes

Post-surgery