5: Anticoagulant drugs Flashcards Preview

Haematology Week 2 2018/19 > 5: Anticoagulant drugs > Flashcards

Flashcards in 5: Anticoagulant drugs Deck (47)
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1

Which clotting times are used to monitor

a) warfarin

b) heparin

activity?

a) INR (which is a standardised method of measuring PT)

b) APTT

2

What are two indications for anti-coagulant drugs?

Venous thrombosis

Atrial fibrillation (increases likelihood of thrombosis)

Thrombophilia

3

Atrial fibrillation can cause (venous / arterial) thrombosis.

either

depending on heart chamber where the blood clots

4

What blood components are activated in

a) venous thrombosis

b) arterial thrombosis?

a) Fibrin

b) Platelets

5

Because of their short half life, Protein C and S levels drop first when a patient is given anticoagulant drugs.

What is the effect of this?

Increased risk of thrombosis (temporary)

6

Which anticoagulant drug enhances the activity of antithrombin?

Heparin

7

What are the two forms and routes of administration of heparin?

Unfractionated heparin (IV)

LMWH (subcut)

8

Name an example of LMWH?

Dalteparin sodium

9

Heparin enhances the activity of ___.

antithrombin

10

Heparin potentiates the activity of antithrombin, a protein which inactivates clotting factors.

Unfractionated heparin enhances the activity of antithrombin against ___.

LMWH enhances the activity of antithrombin against ___.

unfractionated: thrombin

LMWHXa

11

Which anticoagulant drugs are monitored using

a) INR

b) APTT?

a) Warfarin

b) Heparin

12

Which clotting time is used to monitor the activity of unfractionated heparin?

APTT

13

Does LMWH require monitoring?

No

But you can using Anti-Xa assay

14

What is the main side effect of heparin?

Bleeding

15

Heparin can trigger an autoimmune reaction causing which deficiency?

Thrombocytopaenia

16

Name three side effects of heparin.

Bleeding

Thrombocytopaenia (autoimmune)

Osteoporosis (long term use)

17

What happens if you overdose a patient on heparin?

Bleeding

18

Heparin has a (short / long) half life.

short half life

so if bleeding or requiring a procedure you can just stop it

19

In emergencies, which drug can be used to reverse the effects of heparin?

Protamine sulphate

20

Which clotting factors does

a) unfractionated

b) LMW

heparin act on?

a) Thrombin

b) Xa

21

Which anticoagulant drug inhibits the action of Vitamin K?

Warfarin

22

What is the mechanism of action of warfarin?

Inhibits action of Vitamin K

REDUCING ACTIVATION FACTORS II, VII, IX AND X

23

Where are clotting factors produced?

Liver

24

What is required for the production of factors II, VII, IX and X in the liver?

Vitamin K

25

Do patients on warfarin still produce clotting factors?

What is the significance of this?

Yes

The clotting factors are non-functional, need to be activated by Vitamin K

Vitamin K can be used to reverse the effects of warfarin

26

Warfarin has a narrow ___ ___.

therapeutic index

27

Which family of enzymes metabolises warfarin in the liver?

Cytochrome P450

28

Warfarin dosage depends on what?

Patient's INR after first dose of 5 - 10 mg

i.e liver clearance of warfarin by CYP450

29

When should warfarin be taken?

Same time every day

30

Which clotting time is used to measure warfarin response?

INR

Which is a different way of measuring PT