Anticogulant Drugs

Question 1

What are you targeting in prevention of venous thrombosis?

Answer 1

Secondary haemostasis

Question 2

What is a natural inhibitor of fibrin clot formation?

Answer 2

Anti thrombin III

Question 3

What does heparin do?

Answer 3

Potentiates antithrombin

Question 4

How long does it take for heparin to work?

Answer 4

Immediate

Question 5

How do you give heparin?

Answer 5

Subcutaneous

Can also be given IV in rare situations

Question 6

Why isn’t unfractionated heparin used anymore?

Answer 6

Very narrow theraputic window - LMWH is better

Question 7

How does heparin potentiate antithrombin?

Answer 7

Binds to Antithromibin to stabilise the link between it and thrombin or Xa.

Question 8

What test do you use to monitor heparin?

Answer 8

APTT if unfractionated

Anti Xa assay for LMWH but not really used in clinical practice

Question 9

What test do you do to monitor warfarin?

Answer 9

INR (PT)

Question 10

What other assay is occasionally used in heparin monitoring?

Answer 10

Anti Xa

Question 11

Why is APPT used in heparin monitoring?

Answer 11

APPT much more sensitive to heparin therapy

Question 12

Why do you monitor FBC in heparin?

Answer 12

Risk of Heparin Induced Thrombocytopenia (HITT)

If platelet count drops call haematology

Question 13

Give a long term risk of heparin

Answer 13

Osteoporosis

Question 14

What should you do if you get a low platlet count n someone who is on heparin

Answer 14

• Contact haematology
• Stop heparin
  Start other anticoagulant

Question 15

What do you do in the case of bleeding in a patient who is on heparin?

Answer 15

Stop heparin

Question 16

Does heparin have a short of long half life

Answer 16

Short ~ 12 hours

Question 17

What is the antidote to heparin?

Answer 17

Protamine sulphate. This reverses antithrombin effect. Only partially effects LMWH as it does not have an effect on Factor Xa

Question 18

Why does protamine sulphate only partially reverse the effect of LMWH?

Answer 18

Does not have an effect on Factor Xa

Question 19

Where is Vitamin K absorbed?

Answer 19

Upper intestine

Question 20

What dos Vitamin K require for absorption?

Answer 20

Bile salts

Question 21

What clotting factors require Vitamin K?

Answer 21

II
VII
IX
X
Protein C 
Protein S

Question 22

What are the first clotting factors to fall when warfarin is started?

Answer 22

Protein C and S

Question 23

Why do you need to have 5 days of initial heparin therapy with warfarin?

Answer 23

Different half lives of the clotting factors

Question 24

How does vitamin K activate clotting factors?

Answer 24

Carboxylation of glutamic acid

Question 25

Where is warfarin metabolised?

Answer 25

Liver - Cytochrome p450 pathway

Question 26

What metabolises warfarin?

Answer 26

Cytochrome p450

Question 27

How do you start warfarin therapy?

Answer 27

Loading high dose with heparin. Monitor closely and then titrate down If AF and they haven't had a blood clot then start slowly

Question 28

When should warfarin be taken?

Answer 28

At the same time every day

Question 29

What do you use to monitor warfarin therapy?

Answer 29

PT (INR)

Question 30

What is the equation for INR?

Answer 30

PT is seconds/Mean normal PT is seconds x International Sensitivity Index

Question 31

What is the target INR in patients on warfarin?

Answer 31

2 - 3

Question 32

If you have an INR of 5 are you more at risk of bleeding or clotting?

Answer 32

Bleeding

Question 33

What are the side effects of warfarin?

Answer 33

Skin bruising Epistaxis Haematuria

Question 34

What is the risk of an intracerebral haemmorhage in people on warfarin therapy?

Answer 34

1/200 per year

Question 35

How do you reverse warfarin therapy?

Answer 35

1. Omit warfarin dose (this will take several days to get INR back into target range) 2. Oral vitamin K (takes about 6 hours)

Question 36

What do you do if the INR is above 8 or if there is significant bleeding in a patient on warfarin?

Answer 36

Give oral vitamin K

Question 37

What do you do if there is severe bleeding in a patient on warfarin?

Answer 37

1. Stop warfarin 2. Oral Vitamin K 3. Clotting factor administration

Question 38

How long does it take for oral vitamin K to work?

Answer 38

6 hours

Question 39

What do you give to reverse warfarin therapy if you need an immediate reversal?

Answer 39

Clotting factors

Question 40

What are the two classes of new anticoagulants?

Answer 40

Oral direct thrombin inhibitors (Dabigatran) | Oral Xa inhibitors (Rivaroxaban)

Question 41

Name a factor Xa inhibitor?

Answer 41

Rivoroxabam

Question 42

What is the advantage of Xa inhibitors over thrombin inhibitors?

Answer 42

Not renally excreted - won't cause kidney injury

Question 43

What kind of drug is rivoroxabam?

Answer 43

Xa inhibitor