Cardiology: Anti-platelets, anti-coagulants and anti-thrombolytic drugs

Question 1

What forms a white thrombus?

Answer 1

Platelets with a fibrin mesh

Question 2

What forms a red thrombus?

Answer 2

Mainly fibrin

Question 3

Where do white thrombus tend to cause embolisms?

Answer 3

Cerebral- stroke

Question 4

Where do red thrombus tend to cause embolisms?

Answer 4

Pulmonary - PE

Question 5

What is the inactive clotting factor of thrombin?

Answer 5

Prothrombon

Question 6

What do activated clotting factors act as?

Answer 6

Serine proteases

Question 7

Name the process which modifies the precursors in order for them to become activated.

Answer 7

Gamma- carboxylation

Question 8

What is required in order for gamma carboxylation to take place?

Answer 8

Vitamin K in the REDUCED form is a cofactor for the enzyme which catalyses gamma carboxylation

Question 9

What does warfarin do?

Answer 9

Decreased the concentration of reduced vitamin K- less activation of clotting factors=anticoagulation

Question 10

When would you use an anti-coagulant?

Answer 10

To treat a venous thrombosis

Question 11

Give examples of specific incidences in which you would wish to use an anti-coagulant to treat.

Answer 11

DVT and PE
Post operative thrombosis
Prosthetic hear valves
AF

Question 12

How does warfarin prevent the reduction of reduced vitamin K?

Answer 12

Competes with vitamin K for binding to vitamin K reductase

Question 13

At what point does warfarin block coagulation?

Answer 13

In vivo

NOT vitro

Question 14

How is warfarin administered?

Answer 14

Orally

Question 15

Why does warfarin have a slow onset?

Answer 15

Takes time for inactive factors to replace active ones that are cleared slowly from the plasma.

Question 16

Which anticoagulant can be added to have a more rapid anticoagulant effect

Answer 16

Heparin

Question 17

What are the disadvantages of Warfarin?

Answer 17

Risk of haemorrage

Question 18

How can the effect of warfarin be monitored?

Answer 18

By monitoring INR

Question 19

What can increase your risk of haemorrage on warfarin?

Answer 19

Liver disease
Higher metabolic rate
Drug interactions- be careful with aspirin and NSAIDS

Question 20

What factors lessen the action of warfarin?

Answer 20

Pregnancy
Vitamin K in diet
Drug interacton

Question 21

How can you treat an overdose of warfarin?

Answer 21

Vitamin K or plasma clotting factors administration

Question 22

What does antithrombin III do?

Answer 22

Binds to the active site of activated clotting factors and ‘de-activates’ them- inhibits coagulation

Question 23

What does heparin do?

Answer 23

Binds to antothrombin III increasing its affinity for the active clotting factors= ANTICOAGULATION

Question 24

What must heparin do to inhibit IIa?

Answer 24

Bind to both AT III and IIa

Question 25

What must heparin do to inhibit Xa?

Answer 25

It only needs to binds to AT III

Question 26

When is LMWH not preferred?

Answer 26

In renal failure

Question 27

Name two LMWH?

Answer 27

Enoxaparin | Dalteparin

Question 28

What is the difference between LMWH and heparin

Answer 28

LMWH only inhibits Xa not thrombin IIa

Question 29

How is heparin administered?

Answer 29

IV or subcutaneously( LMWH)

Question 30

How is LMWH eliminated from the body?

Answer 30

Renal excretion

Question 31

What order kinetics does HMWH show?

Answer 31

First

Question 32

What order kinetics does heparin show?

Answer 32

Zero

Question 33

How is optimum dosage determined for heparin? (NOT LMWH)

Answer 33

In vitro clotting test

Question 34

Give the adverse affects of heparin.

Answer 34

Haemorrage Osteoporosis Hypoaldosternism Hypersensitivity reactions

Question 35

Name an orally administered drug that directly inhibits thrombin

Answer 35

Dabigatran etexilate

Question 36

Name an orally administered drug that directly inhobots factor Xa

Answer 36

Rivaroxaban

Question 37

When are dabigatran and rivaroxaban used?

Answer 37

Prophylactically in hip and knee replacements

Question 38

What initially stimulates platelet aggregation?

Answer 38

Endothelial damage or plaque rupture

Question 39

How do platelets adhere to the endothelium?

Answer 39

GPlB receptors and VWF

Question 40

Name substances that increase the expression of GPIIB/IIIA receptors and this cause aggeegtion.

Answer 40

ADP 5-HT and TXA2

Question 41

What enzyme synthesises thromboxane A2?

Answer 41

COX- cyclooxygenase

Question 42

What does acidic phospholipids on platelet surface cause?

Answer 42

Promotion of thrombon formation

Question 43

When are anti-platelet drugs used?

Answer 43

To treat arterial thrombosis

Question 44

Name three anti platelet drugs.

Answer 44

Aspirin Clopidogrel Tirofibrin

Question 45

How does aspirin work?

Answer 45

Irrevesible COX inhibitor- prevents TXA2 synthesis and production of prostaglandin.

Question 46

What is the advese affect of aspirin?

Answer 46

GI ulceration and bleeding

Question 47

How does clopidogrel work?

Answer 47

Irrevesibly blocks the P2Y12 receptors- decreased in ADP

Question 48

When is clopidogrel used?

Answer 48

Synergistically with aspirin | When intolerant of aspirin

Question 49

How does tirofiban worK?

Answer 49

Prevents convertion of fibringogen to fibrin

Question 50

When is tirofiban used?

Answer 50

Given IV in short term to prevent MI in patients with unstable angina

Question 51

What do fibrinolytic drugs do?

Answer 51

Break down fibrin and thus dissolve thrombi

Question 52

What breaks down the fibrin?

Answer 52

Plasmin

Question 53

How do fibrinolytic drugs work?

Answer 53

Activate plasmin from the inactive plasminogen

Question 54

When are fibrinolytic drugs used?

Answer 54

Actue MI or stroke if PCI not available

Question 55

Name three fibrinolytic drugs

Answer 55

Streptokinase Altepase Duteplase

Question 56

What is streptokinase.

Answer 56

Protein from streptococci. | Antibodies form against it after four days

Question 57

What is the risk of streptokinase?

Answer 57

Allergic reaction

Question 58

How do alteplases and duteplase work?

Answer 58

They are recomboninent tissue plasminogen activators

Question 59

How are fibrinolytic drugs administered?

Answer 59

IV- short half life

Question 60

What is the adverse affects of alteplase and duteplase?

Answer 60

Haemorrhage

Question 61

How can haemorrage in fibrinolytics be controlled?

Answer 61

Tranexamic acid- inhibits plasminogen activation.