B.9 Anticoagulation

Question 1

Which one of the following best describes the action of warfarin?

a. it inhibits platelet aggregation
b. it inhibits coagulation
c. It thins the blood
d. it controls atrial fibrillation
e. it is thrombolytic

Answer 1

b. It inhibits coagulation

Question 2

What is the use of anticoagulants?

Answer 2

Used to prevent coagulation

Question 3

What is the most commonly used injectable anticoagulant?

Answer 3

LMWH

Question 4

How does heparin work pharmacologically?

Answer 4

1. Heparin binds and activates the natural protein antithrombin III
2. This inhibits the serine protease activity of a range of coagulation factors

Question 5

How quickly do heparins work?

Answer 5

They work immediately as they directly interfere with the coagulation cascade

Question 6

\how long does warfarin take to act?

Answer 6

Takes about 3 days

Question 7

Why are heparin and warfarin given to patients at the same time?

Answer 7

Warfarin takes about 3 days to act, so whilst the patient is waiting for the effects of warfarin, heparin can be given for a more immediate effect.

Question 8

Do unfractionated heparins require coagulation monitoring?

Answer 8

Yes, as the effects are less predictable than LMWH

Question 9

What can happen if heparin is used for more than 5 days?

Answer 9

Can lead to thrombocytopenia, which means that immune cells start to attack platelets

Therefore it is important to monitor platelet count

Question 10

What are the signs and symptoms of deep vein thrombosis?

Answer 10

Painful swelling in the calm

Question 11

What is the diagnosis of DVT?

Answer 11

Ultrasound scan

Question 12

What should you look for when assessing blood samples for DVT

Answer 12

Increased levels of D-dimer

D-dimer is a product of fibrinolysis and is raised in thrombosis

Question 13

What is the key use of anticoagulants?

Answer 13

Used to prevent unwanted thrombosis

Question 14

Why is vitamin K important in coagulation?

Answer 14

Vit K is responsible for the correct production of cofators

Question 15

What is the pharmacological target for warfarin?

Answer 15

Warfarin blocks the vitamin K reductase, needed for vitamin K to work as a cofactor.

Question 16

Where are the coagulation factors produced?

Answer 16

Liver

Question 17

Describe the pharmacological action of warfarin in the body.

Answer 17

1. New protein produced undergoes post-transitional modification involving carboxylation of glutamic acid residues to produce the correct coagulation factors
   (this is a vitamin dependent reaction)
2. Warfarin is a vitamin K antagonist, therefore prevents the correct formation of coagulation factors

Question 18

what is the major use of warfarin?

Answer 18

Used to prevent thrombosis

• In patients who have replaced heart valves
• AF
• PE
• DVT

Question 19

What does INR stand for?

Answer 19

International normalized ratio