Anticoagulants

Question 1

Define Anticoagulants

Answer 1

Drugs used to prevent coagulation

Question 2

What are the two main types of anticoagulants?

Answer 2

Injectable anticoagulants ie. Heparins

Oral anticoagulants ie. Warfarin

Question 3

What are the two main types of heparins?

Answer 3

Unfractionated Heparin

Low Molecular Weight Heparins (Enoxaparin, Tinzaparin)

Question 4

How do heparins work?

Answer 4

Activate Antithrombin III

AIII inactivates clotting factors/thrombin by complexing w/ serine protease of the factors

Question 5

When should heparin be used?

Answer 5

Immediate action
Used while Warfarin takes effect
Used to prevent thrombosis/clotting on collecting

Question 6

What marker should be monitored during the use of unfractionated heparins?

Answer 6

Activated Partial Thromboplastin Time (APTT)

Question 7

Which pathway does APTT examine?

Answer 7

Intrinsic pathway

Altered by changes in F XII, XI, IX, VIII, X, V, II, I

Question 8

Do LMWHs require monitoring?

Answer 8

No

Question 9

What effect does treatment with heparin have on platelets?

Answer 9

> 5 days heparin can lead to thrombocytopenia

Question 10

Define DVTs

Answer 10

Deep Vein Thrombosis

Question 11

What is a major secondary risk of DVTs

Answer 11

Pulmonary Embolism

Question 12

What is a major cause of DVTs

Answer 12

Immobility in hospital

Question 13

What are the signs/symptoms of DVTs?

Answer 13

Painful swelling in calf

Question 14

What is diagnosis of DVT based on?

Answer 14

Ultrasound scan

D-dimer blood test

Question 15

What are D-dimers?

Answer 15

Product of fibrinolysis raised in thrombosis

Question 16

What are the risk factors for DVT/PE?

Answer 16

Surgery
Pregnancy
Oestrogens
Malignancy
MI/Heart Failure
Obesity
Age >40
Coagulation Disorders
Immobility
History of VTE
Trauma

Question 17

What is the regular drug treatment for DVTs in hospital?

Answer 17

Enoxaparin s.c.

Question 18

How does Warfarin work?

Answer 18

Vitamin k antagonist (blocks Vit. K reductase)

Vit K essential for prothrombin AND F X, IX, VI (1972) production

Question 19

When is Warfarin used?

Answer 19

Patients w/ replaced heart valves
Atrial Fibrillation
DVT/PE

Question 20

What are the problems with using Warfarin?

Answer 20

Many drug interactions
Narrow therapeutic window
Several days to act

Question 21

What is the INR?

Answer 21

International Normalised Ratio
Measure of clotting time based on prothrombin time
Ideally I

Question 22

What is the Prothrombin Time?

Answer 22

Time for coagulation following addition of thromboplastin

Question 23

What abnormalities prolong the Prothrombin Time?

Answer 23

Abnormalities of F VII, X, V, II, I
Liver Disease
Warfarin

Question 24

What is the effect of increased Warfarin action?

Answer 24

Bleeding:

• Gastric
• Cererbral
• Haemoptysis
• Blood in faeces
• Blood in urine
• Easy bruising

Question 25

How should Warfarin dosing/monitoring take place?

Answer 25

INR frequently monitored at start (2/wk) then increase interval (max 12 wks)

Question 26

How can Warfarin dosing be reversed?

Answer 26

Vitamin K

Question 27

When should Warfarin dosing be reversed?

Answer 27

Patient is bleeding Very high INR (>8-10) Warfarin overdose

Question 28

How should patients be counselled about taking Warfarin?

Answer 28

``` Stick to regimen Take at 6 pm If dose missed DON'T take two, inform Dr Don't take when pregnant Consume alcohol in moderation ```

Question 29

What dietary modifications should be made when treated with Warfarin?

Answer 29

Avoid excessive green vegetables | Avoid high levels of Vit K

Question 30

What symptoms should patients be aware of and notify their doctors over?

Answer 30

``` Haemoptysis Blood in faeces Blood in urine Nose bleeds (>20-30 mins) Easy bruising Skin changes (necrosis) Diarrhoea/Vomiting >2days ```

Question 31

What factors affect anticoagulant treatment in pregnant women?

Answer 31

Pregnancy produces thrombophilic state to prevent post partum haemmorhage Thrombophilia - decreased venous return (gravid uterus/immobility)

Question 32

Why should Wafarin be avoided in pregnant women?

Answer 32

Teratogenic (Chondroplasia punctata, optic atrophy, mental retardation) Avoid in T1/3 Favour LMWHs

Question 33

What is Dabigatran?

Answer 33

Oral thombin inhibitor

Question 34

What are the benefits of Dabigatran over Warfarin?

Answer 34

Less bleeding Fewer interactions Does not require monitoring EQUALLY EFFECTIVE

Question 35

What is Rivaroxaban?

Answer 35

Oral inhibitor of activated F X

Question 36

What is Dipyridamole?

Answer 36

Antiplatelet drug | Phosphodiesterase inhibitor

Question 37

How does Dipyridamole work?

Answer 37

Phosphodiesterase inhibitor Prevents cAMP/cGMP breakdown Inhibits aggregation

Question 38

What is Streptokinase?

Answer 38

Thrombolytic medication | Fibrinolysis

Question 39

How does Streptokinase work?

Answer 39

Activates endogenous fibrinolysis system

Question 40

When is Streptokinase used?

Answer 40

Breakdown clots immediately after MI