5: Anti-platelet, anticoagulant and thrombolytic drugs

Question 1

What is haemostasis?

Answer 1

Arrest of blood loss from a damaged vessel

(stopping bleeding)

Question 2

What is the sequence of events of haemostasis?

Answer 2

Vasodilation at site of injury

Platelets arrive at site of injury

Formation of fibrin (blood coagulation)

Question 3

What is exposed when a vascular wall is damaged?

Answer 3

Collagen

Tissue factor (receptor)

Question 4

Which protein helps with the adhesion, activation and aggregation of platelets to damaged blood vessels?

Answer 4

Fibrinogen

Question 5

When fibrinogen triggers the aggregation of platelets, what forms in the blood vessel?

Answer 5

Soft plug

Question 6

What is fibrinogen converted into during coagulation?

Answer 6

Fibrin

Question 7

What is thrombosis?

Answer 7

Pathological haemostasis i.e a clot forms without prior bleeding

Question 8

Virchow’s triad shows the predisposing factors for ___.

Answer 8

thrombosis

Question 9

What are the three prothrombotic factors of Virchow’s triad?

Answer 9

Injury to vessel wall

Abnormal blood flow

Increased coagulability of blood

Question 10

An arterial thrombus is also known as a ___ thrombus.

Answer 10

white

Question 11

What does a white thrombus consist of?

Answer 11

Platelets in a fibrin mesh

Question 12

When a white thrombus detaches from its site of origin, it may form an ___.

Answer 12

embolus

Question 13

Which drugs are used to treat white thrombi?

Answer 13

ANTIPLATELET DRUGS

Question 14

A venous thrombus is also known as a ___ thrombus.

Answer 14

red

Question 15

Which drugs are used to treat red thrombi?

Answer 15

ANTICOAGULANT DRUGS

Question 16

Where do emboli from white thrombi usually lodge?

Answer 16

Coronary arteries

Carotids

Subarachnoid

Question 17

Where do emboli from red thrombi usually lodge?

Answer 17

Pulmonary arteries

(PE)

Question 18

Which drug blocks modification of factors X and II?

Answer 18

Warfarin

Question 19

What drug directly inhibits activated factor X (Xa)?

Answer 19

Rivaroxiban

Question 20

Which drugs indirectly block activated factor X (Xa)?

Answer 20

Heparins

Fondaparinux

Question 21

Which drug directly inactivates activated factor II (IIa), which is responsible for thrombin production?

Answer 21

Dabigatran

(Heparin also does, indirectly)

Question 22

___ factors act as precursors for ___ factors.

Answer 22

inactive , active

Question 23

Which sort of enzyme do inactive precursor factors act as?

Answer 23

Serine proteases

Question 24

Which process do precursor factors undergo to become active factors?

Answer 24

gamma carboxylation

Question 25

What is required for gamma carboxylation of inactive precursor factors to active factors?

Answer 25

**Vitamin K**

Question 26

Which enzyme, important in gamma carboxylation of inactive precursor factors, does warfarin act on?

Answer 26

**Vitamin K reductase**

Question 27

What acts (with a delay) on vitamin K reductase to bring about an anticogulative effect?

Answer 27

**Warfarin**

Question 28

How long does it take for warfarin to produce an anticoagulative effect?

Answer 28

**2-3 days**

Question 29

Which type of thrombosis are **anticoagulants** used to treat?

Answer 29

**Venous / red thrombosis**

Question 30

Give an example of a case where an anticoagulant drug would be used to prevent **venous thrombosis** and **embolism.**

Answer 30

DVT Post-surgery Artificial heart valves Atrial fibrillation

Question 31

What is a significant risk when using anticoagulative drugs like warfarin?

Answer 31

**Haemorrhage**

Question 32

How is warfarin administered?

Answer 32

**Oral**

Question 33

Which drug produces a **rapid anticoagulant effect?**

Answer 33

**Heparin** (or a LMWH)

Question 34

How many **half-lives** would you clear a drug (e.g heparin) for before commencing a procedure which required its absence?

Answer 34

**5 half-lives** (200 hrs in case of warfarin)

Question 35

What property of warfarin makes it difficult to strike a balance between **desired anticoagulant effect** and **haemorrhage**?

Answer 35

**Low therapeutic index**

Question 36

Which factors increase the risk of haemorrhage when using warfarin?

Answer 36

**Liver disease** **High metabolic rate** (hyperthyroidism?) **Loads of drug interactions**

Question 37

Which factors increase the **risk of thrombosis** when using warfarin?

Answer 37

**Pregnancy** **Hypothyroidism** **Vitamin K consumption** **Loads of drug interactions**

Question 38

If someone took too much warfarin and haemorrhaged, what would you give them?

Answer 38

**Vitamin K** plasma clotting factors

Question 39

What does antithrombin III resist the effect of?

Answer 39

**Thrombin**

Question 40

What process does **antithrombin III** inhibit?

Answer 40

Coagulation

Question 41

Which drug binds to antithrombin III to increase its effect?

Answer 41

**Heparin**

Question 42

Which factors does antithrombin III act on to produce an anticoagulative effect?

Answer 42

**Xa** and **IIa**

Question 43

Name a **low molecular weight heparin** (LMWH).

Answer 43

**Dalteparin** **Enoxaparin** **Fondaparinux** Idrabiotaparinux

Question 44

LMWHs act on antithrombin III to inhibit activated factor \_\_.

Answer 44

**Xa**

Question 45

How is heparin administered?

Answer 45

**IV** (immediate onset) **Subcutaneously** (works within an hour)

Question 46

Heparin is the preferred anticoagulant in which type of organ failure?

Answer 46

**Renal failure**

Question 47

Name two other anticoagulative drugs (other than warfarin and heparin).

Answer 47

**Dabigatran** **Rivaroxaban**

Question 48

Which drug blocks ADP channels on platelets?

Answer 48

**Clopidogrel**

Question 49

Which drug blocks COX-1? lol

Answer 49

**Aspirin**