Drugs affecting blood coagulation, platelet aggregation, fibrinolysis

Question 1

Fibrinoytic drugs are used to treat…

Answer 1

• are used to treat cardiovascular thrombosis

Question 2

Heparin inhibits action of _______

Answer 2

inhibits action of thrombin, Factors X & IX

Question 3

Which of the following drugs interferes with the COX enzyme?

• Warfarin
• Aspirin
• Aprotonin
• Heparin

Answer 3

Aspirin

Question 4

Haemostasis is

Answer 4

A delicate balance between the normal function of blood and preventing blood loss following vessel damage

Question 5

What is a thrombosis ?

Answer 5

Formation of a thrombus (blood clot) within a vessel

Initiated by:
pooling of blood in veins due to sluggish flow (e.g. DVT in calf after long flights)

Question 6

what is an embolus?

Answer 6

Fragment or whole thrombus detached from blood vessel wall

Travels through blood vessels

Blocks small blood vessels in pulmonary, cardiac, CNS circulation

   pulmonary embolism (PE)
  myocardial infarction (MI)
  stroke

Question 7

Targets for modifying thrombosis process?

Answer 7

Modify coagulation
most successful in venous thrombosis

Modify platelet aggregation
important in arterial thrombosis

Modify clot, thrombus breakdown
after prophylaxis fails

Question 8

Inhibit thrombus formation

without _____ _______.

Answer 8

Inhibit thrombus formation
without
Preventing haemostasis

Question 9

what is the action of heparin?

Answer 9

Activates ANTITHROMBIN (AT)

Activated AT forms complexes with activated clotting factors: THROMBIN, Factors Xa (and FIXa & XIa to a lesser extent) inactivating them

Heparins increase :

- rate of complex 
- formation

Question 10

What are the problems with heparin?

Answer 10

Poorly absorbed from oral administration
Give intravenously or subcutaneously

Risk of haemorrhage
Mild: cease administration
Severe: protamine sulphate- forms complex with heparin, no longer has anticoagulant effect

Question 11

What is the orally anticoagulant?

Answer 11

Warfarin

Question 12

What are the actions of Warfarin ?

Answer 12

Mechanism of Action. Warfarin acts by inhibiting the synthesis of vitamin K-dependent clotting factors, which include Factors II, VII, IX, and X, and the anticoagulant proteins C and S. Vitamin K is an essential cofactor for the post ribosomal synthesis of the vitamin K-dependent clotting factors

Question 13

What are the problems of Warfarin?

Answer 13

+Slow onset

• Pre-existing factors need to be depleted
• Variation in half-life between clotting factors
• After administration patient is only fully anticoagulated after 3 days (starting regimen)

+Activity influenced by Vitamin K

+Many interactions: drugs, foods etc

+Risk of haemorrhage

Avoid in late pregnancy, haemorrhage in newborn

+Teratogenic
Avoid in early pregnancy