Drugs affecting blood clotting and thrombosis

Question 1

What is thrombosis?

Answer 1

Formation of thrombus (blood clot) in a vessel.
Initiated by:
-Pooling of blood in veins due to sluggish flow.
-Damaged vessels
-Atheromatous plaques

Question 2

What is an embolus?

Answer 2

When a thrombus becomes detached and blocks small blood vessels in pulmonary, cardiac and CNS circulation.
Can cause:
-pulmonary embolism
-Myocardial infarction
-Stroke

Question 3

What is haemostasis?

Answer 3

Balance between normal function of blood and preventing blood loss following vessel damage.

Question 4

What do you know about Heparin?

Answer 4

Natural anticoagulant in liver lungs and mast cells

Activates antithrombin to form complexes with clotting factors: THROMBIN and Xa

Question 5

Problems with heparin

Answer 5

Has to be given intravenously or subcutaneously

Risk of haemorrhage

Question 6

What do you know about Warfarin?

Answer 6

Anticoagulant

Antagonises vitamin K role in formation of clotting Inhibits factors 2(prothrombin), 7&9 being activated.

Question 7

Problems with warfarin

Answer 7

Slow onset
Activity influenced by vitamin K
Interacts with lots of things; drugs, food etc
Risk of haemorrhage
Teratogenic

Question 8

What do you know about Rivaroxaban?

Answer 8

Oral inhibitor of FXa

potential to replace warfarin

Question 9

What do you know about Dabigatran?

Answer 9

Oral thrombin inhibitor with potential to replace warfarin

Question 10

What are the 3 targets for antiplatelet drugs?

Answer 10

1- Reduce synthesis of thromboxane A2 (ASPIRIN)
2- Increase cAMP in platelets (DIPYRIDAMOLE)
3- Reduce glycoprotein receptors on platelets (CLOPIDOGREL)

Question 11

What do you know about Aspirin?

Answer 11

Antiplatelet drug

Irreversibly blocks platelet COX enzyme to reduce thromboxane synthesis.

Question 12

What do you know about Dipyridamole?

Answer 12

Antiplatelet drug
Inhibits PDE enzyme 
Prevents breakdown of cAMP in platelets 
Decreases platelet aggregation 
Blocks adenosine uptake
Inhibits TXA2 synthesis

Question 13

What do you know about Clopidogrel?

Answer 13

Antiplatelet drug
Inhibits glycoprotein 11b & 111a on platelets.
Inhibits ADP receptor

Question 14

What do fibrinolytic drugs do?

Answer 14

Dissolve pre-existing clot or thrombus

Question 15

What do you know about Alteplase?

Answer 15

Binds to plasminogen with fibrin strands to convert inactive plasminogen into active plasmin. Plasmin digests fibrin and dissolves thrombus.

Question 16

What do you know about Streptokinase?

Answer 16

Used to dissolve clots or thrombus.

Question 17

What do you know about Tranexamic acid?

Answer 17

Reduces activation of plasminogen to plasmin and it is used in situations where there is a risk of bleeding.