Anti-thrombotic therapy

Question 1

What is the most important feature of the haemostatic system?

Answer 1

Maintain integrity of vascular endothelium

Maintain blood fluidity (balance between haemorrhage and thrombosis)

Question 2

What is a thrombus?

Answer 2

Solid clot made by platelets, fibrin and trapped blood cells

Question 3

What is primary thrombosis?

Answer 3

Partial or total obstruction of blood vessel by thrombi

Question 4

What is an embolism?

Answer 4

Migration of a clot or part of it to another site

Question 5

What is a thromboembolism?

Answer 5

Obstruction of blood vessel by a clot that has become dislodge from another site in circulation

Question 6

What can cause endothelial damage?

Answer 6

Trauma
Catheterisation 
Neoplasia
Parasites
Amyloidosis

Question 7

What can cause hyperviscosity of blood?

Answer 7

Dehydration
Leukaemia
Hyperglobulinaemia
Hyeprfibrinogenaemia

Question 8

What can cause hypecoaguability of the blood?

Answer 8

Platelet hyperaggregability
Reduced coagulation factors
Hypofibronolysis

Question 9

What are the 2 types of anti-thrombotic therapies?

Answer 9

Thrombolytics - for existing thrombi

Preventive - prevent new thrombi formation

Question 10

Give examples of thrombolytic treatments (break down blood clots)

Answer 10

Surgical extraction
Recombinant tissue plasminogen activates (rt-PA)
Streptokinase
Urokinase

Question 11

What does rt-PA (recombinant tissue plasminogen activator) do? What are the risks? Give an example

Answer 11

Increase transformation of plasminogen to plasmin
Spontaneous bleeding
Reteplase

Question 12

What produces streptokinase? What does it do?

Answer 12

Streptococci bacteria

Enhances plasmin formation

Question 13

What is plasmin?

Answer 13

Enzyme that degrades fibrin clots

Question 14

When may streptokinase may not be an effective thrombolytic?

Answer 14

If had previous streptococcus infection, as have streptococcus antibodies

Question 15

How does urokinase work?

Answer 15

Activates plasminogen (which causes plasmin formation, which degrades fibrin clots))

Question 16

What are the 3 types of preventive anti-thrombotic treatments?

Answer 16

Anti platelet drugs
Heparin
Vitamin K antagonists

Question 17

How do vitamin K antagonists work as preventive anti-thrombotics?

Answer 17

Vitamin K required for coagulation factors

Less vitamin K - less coagulation

Question 18

Anti-PLT drugs can be COX inhibitors, ADR-receptor agonists and more. Give an example of a COX inhibitor. Are the effects permanent or temporary? What are side effects?

Answer 18

Aspirin
Permanent - last platelet lifetime (7 days)
GI ulcers (antiprostaglandin) and kidney damage

Question 19

Give an example of an ADR receptor antagonist used as a preventive antithrombotic

Answer 19

Clopidogrel

Question 20

What are the 2 types of heparin?

Answer 20

Unfractioned heparin

Low molecular weight heparin

Question 21

What are the advantages of low molecular weight heparin drugs?

Answer 21

More predictable pharmacokinetics

Longer half life

Question 22

In an arterial thrombosis, what is predominant? What should therapy target? Give 2 examples of treatment

Answer 22

Platelets

Platelet aggregation - aspirin, clopidogrel

Question 23

In venous thrombosis, what is predominant? What should therapy target? Give an example of treatment

Answer 23

Fibrin and RBCs dominant
Target secondary haemostasis
Heparin

Question 24

If a thrombus is of unknown location (arterial or venous), what treatment should be used?

Answer 24

Combined

Therapy against PLT aggregation (arteries) and therapy against secondary haemostasis (venous)