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Flashcards in Anticoagulant drugs Deck (46)
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1
Q

anticoagulants are used for arterial/venous thrombosis

A

venous

2
Q

what are the main indications for anticoagulants

A

DVT

atrial fibrillation

3
Q

venous clots are platelet/fibrin rich

A

fibrin

4
Q

what types of anticoagulants are there

A

heparin
warfarin
DOACs

5
Q

how does heparin work

A

enhances the natural anticoagulation system by potentiating the effects of anti thrombin
anti thrombin inhibits thrombin and Xa

6
Q

heparin has an immediate/delayed effect

A

immediately effective

7
Q

the therapeutic index of heparin and warfarin are wide/narrow

A

narrow

8
Q

when heparin binds to antithrombin it enhances thrombin/Xa inhibition more

A

thrombin

9
Q

when LMWH binds to antithrombin it enhances

thrombin/Xa inhibition more

A

Xa

10
Q

how is unfractionated heparin administered

A

IV

11
Q

how is LMWH administered

A

SC

12
Q

which needs more monitoring, unfractionated heparin or LMWH

A

unfractionated heparin

13
Q

how do you monitor unfractionated heparin

A

APTT

14
Q

how can you monitor LMWH

A

anti-Xa assays

15
Q

why is APTT measured for heparin

A

heparin will eventually decrease both PTT and APTT but because of the effect thrombin has on factors 8+9 (intrinsic pathway) APTT is more sensitive to change

16
Q

what are complications of heparin

A

bleeding
immune reaction: heparin induced thrombocytopaenia with thrombosis HITT
osteoporosis in the long term

17
Q

how do you reverse heparin

A

stop heparin

if severe bleeding:
protamine sulphate

18
Q

heparin has a short/long half life

A

short

19
Q

what is the antidote to heparin overdose

A

protamine sulphate

20
Q

what group of drugs does warfarin belong to and what is their mechanism of action

A

Coumarin anticoagulant group

Vit K antagonists

21
Q

Vit K is fat/water soluble

A

fat

22
Q

what are the vitamin K dependent factors and where are they made

A

2,7,9,10
Protein C+S
produced by the liver

23
Q

why is it important that carboxylation of clotting factors by vit K occurs

A

this allows clotting factors to effectively bind to platelet plug

24
Q

When you start warfarin, levels of which proteins go down

What is a consequence of this

A

Protein C+S

causes you to become prothrombotic initially

25
Q

why should you not start warfarin alone immediately after a VTE
what should be given alongside

A

heparin

because of increased thrombosis risk initially

26
Q

which enzyme in the body causes the required dose of warfarin to be different in individuals

A

Cytochrome P450

27
Q

how is warfarin monitored

A

INR
internationalised normalised ratio
standardised across the world

28
Q

what is the ideal target INR

A

2-3

29
Q

what are complications of warfarin therapy

A

bleeding
co-morbidities
DRUG INTERACTIONS

30
Q

what should be measured if a patient on warfarin starts a new drug

A

INR

31
Q

what should be done if a patient on warfarin has a high INR and has bruises

A

omit doses of warfarin

32
Q

what can you give to quickly reduce INR

A

PO vitamin K

33
Q

what should be done in a patient on warfarin who is bleeding severely

A

stop warfarin
Vitamin K
clotting factors 2,7,9,10

34
Q

how fast do Vit K and clotting factors work

A

vit K - 6 hours

clotting factors - immediately

35
Q

indications for warfarin

A

metal heart valves

APLS

36
Q

what are DOACs

A

Direct oral anticoagulants

newer agents that directly target Xa or thrombin

37
Q

how are DOACs administered

A

PO

38
Q

why are DOACs more favourable to use

A

no monitoring required

less drug interactions

39
Q

give an example of a direct thrombin inhibitor

A

dabigatran

40
Q

what is the method of action of dabigatran

A

inhibits thrombin which means fibrin cannot form from fibrinogen

41
Q

where is dabigatran metabolised and excreted

A

kidneys

42
Q

give examples of direct Xa inhibitors

A

rivaroxiban, apixaban, edoxiban

43
Q

how does rivaroxiban work

A

inhibits factor Xa and so prevents thrombin formation

44
Q

indications for DOACs

A

prophylaxis in joint replacement surgery
DVT/PE
stroke prevention in AF

45
Q

what can potentiate the action of warfarin and what is a consequence

A

liver disease/cirrhosis
high metabolic activity
drug interactions

Bleeding risk

46
Q

what can lessen the action of warfarin and what is a consequence

A

Pregnancy
hypothyroidism
Vitamin K consumption
drug interactions

clot formation