Anti-Coagulant Drugs Flashcards

1
Q

what are two indications for anticoagulants?

A

venous thrombosis
AF - stroke prevention

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2
Q

what do anticoagulant drugs target?

A

the formation of the fibrin clot

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3
Q

name three types of anti coagulant

A

heparin
warfarin
DOACs

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4
Q

how does heparin work?

A

potentiates the naturally occurring anti-coagulant, anti thrombin

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5
Q

how long does it take for heparin to have an effect?

A

immediate

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6
Q

what are the two possible routes of administration of heparin?

A

IV
SC

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7
Q

what are the two forms of heparin?

A

unfractionated

low molecular weight (LMWH)

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8
Q

what is the MoA of unfractionated heparin?

A

binds to the complex of anti-thrombin and thrombin, keeping it together and stabilising it = more clot breakdown

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9
Q

what is the MoA of LMWH?

A

binds to anti-thrombin bound to factor Xa to prevent it from being deactivated

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10
Q

which type of heparin requires close monitoring due to its less predictable responses?

A

unfractionated

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11
Q

which type of heparin can be given at fixed doses?

A

LMWH

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12
Q

what effect does heparin have on coagulation screen results?

A

PT and APTT will be prolonged

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13
Q

what should be monitored when giving unfractionated heparin?

A

APTT

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14
Q

what can be monitored to assess LMWH in complex patients?

A

anti-Xa assay

not usually needed

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15
Q

what is the main risk of heparin use?

A

bleeding

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16
Q

what is a possible rare complication of heparin?

A

heparin induced thrombocytopenia with thrombosis (HITT)

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17
Q

what should be monitored in patients on heparin in case of HITT?

A

FBC

18
Q

what causes HITT with heparin use?

A

when heparin results in antibody formation

19
Q

what complication can be caused by long term heparin use?

A

osteoporosis

20
Q

what can be done to reverse heparin in most cases and why?

A

stop giving it

very short half life

21
Q

what can be given to reverse heparin in severe bleeding?

A

protamine sulphate

complete reversal for unfractionated, partial for LMWH

22
Q

name four coumarin anticoagulants

A

warfarin
phenindione
acenocoumarin
phenprocoumon

23
Q

what is the MoA of warfarin?

A

inhibition of vitamin K leading to the synthesis of non functional coagulation factors

24
Q

what are the vitamin K dependent proteins involbed in haemostasis?

A

factors 2,7,9 and 10

protein C and S

25
Q

what should be given when starting on warfarin and why?

A

heparin

initially increased risk of clots due to lack of protein C and S, goes away after around 5 days

26
Q

when should patients take warfarin?

A

at the same time everyday

27
Q

how is warfarin response monitored?

A

INR

28
Q

what is the target INR for most patients on warfarin?

A

2-3

29
Q

what does a higher INR suggest?

A

less likely to thrombose, more likely to bleed

30
Q

what can be done to reverse warfarin if there is minor bleeding, to bring INR down over a few days?

A

omit warfarin doses

31
Q

what should be done to reverse warfarin if INR>8?

A

administer oral vitamin K

32
Q

how long does it take for oral vitamin K to reverse warfarin?

A

around six hours

33
Q

what should be given for immediate reversal of warfarin in severe bleeding?

A

clotting factor concentrates

34
Q

what are the two types of DOACs?

A

oral direct thrombin inhibitors
oral Xa inhibitors

35
Q

what monitoring is required for DOACs?

A

none

36
Q

name an oral direct thrombin inhibitor

A

dabigatran

37
Q

how do oral direct thrombin inhibitors work?

A

target thrombin, preventing the fibrin clot from forming

also prevent factors 8+9 being activated

38
Q

when are direct thrombin inhibitors contraindicated and why?

A

patients with renal problems as they are renally excreted

39
Q

which type of DOAC is more commonly used?

A

oral Xa inhibitors

40
Q

how do oral Xa inhibitors work?

A

directly inhibit Xa

41
Q

name three oral Xa inhibitors

A

edoxaban
rivaroxaban
apixaban