Anticoagulant, Anti-platelet and Thrombolytic Drugs

Question 1

Haemostasis

Answer 1

Arrest of blood loss blood from damaged vessel

Question 2

Haemostasis pathogenesis

Answer 2

1. Vascular wall damage, exposes collagen and tissue factors
2. Local vasoconstriction
3. Platelet adhesion, activation and aggregation
4. Activation of blood clotting and formation of a stable clot

Question 3

TXA2

Answer 3

Synthesised and released by activated platelets
Binds to receptors releasing serotonin and ADP
ADP binds to platelet GPCR activating further platelets

Question 4

Thrombosis

Answer 4

Pathological haemostasis

Question 5

Arterial thrombus

Answer 5

White
Mainly platelets in a fibrin mesh
Forms embolus if detaches that often lodges in brain
Treated with anti-platelet drugs

Question 6

Venous thrombus

Answer 6

Red
Jelly-red tail and fibrin rich
Forms embolus if detached that will often lodge in lung
Treated with anticoagulants

Question 7

Warfarin

Answer 7

Anticoagulant 
Competitive inhibitor of vitamin K 
Blocks in vivo not in vitro
Slow onset of action, long half life
Low therapeutic index
Risk of haemorrhage

Question 8

Risk factors for haemorrhage on warfarin

make warfarin work too well

Answer 8

Liver disease
High metabolic rate
Drugs inhibiting platelet function (aspirin)
Drugs that decrease availability of vitamin K

Question 9

Factors that increase risk of thrombosis on warfarin

don’t allow warfarin to work well enough

Answer 9

Physiological state (pregnancy)
Vitamin K consumption
Drugs that increase metabolism of warfarin

Question 10

Heparin

Answer 10

Anti-coagulant
Binds to antithrombin III, increasing affinity for serine protease clotting factors , increasing rate of their activation

Question 11

Adverse effects of heparin

Answer 11

Haemorrhage
Osteoporosis (longer term)
Hypersensitivity reactions

Question 12

Anti-platelet drugs

Answer 12

used for arterial thrombosis

Question 13

Anti-coagulant drugs

Answer 13

used for venous thrombosis

Question 14

Aspirin

Answer 14

Irreversibly blocks COX, preventing TXA2 synthesis and inhibits production of antithrombotic prostoglandin

Question 15

Adverse effects of aspirin

Answer 15

GI bleeding and ulceration

Question 16

Clopidogrel

Answer 16

If intolerant to aspirin

Question 17

Tirofiban

Answer 17

Prevent MI

Manage unstable angina