Anti-Coagulant Drugs

Question 1

what are two indications for anticoagulants?

Answer 1

venous thrombosis
AF - stroke prevention

Question 2

what do anticoagulant drugs target?

Answer 2

the formation of the fibrin clot

Question 3

name three types of anti coagulant

Answer 3

heparin
warfarin
DOACs

Question 4

how does heparin work?

Answer 4

potentiates the naturally occurring anti-coagulant, anti thrombin

Question 5

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

Answer 5

immediate

Question 6

what are the two possible routes of administration of heparin?

Answer 6

IV
SC

Question 7

what are the two forms of heparin?

Answer 7

unfractionated

low molecular weight (LMWH)

Question 8

what is the MoA of unfractionated heparin?

Answer 8

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

Question 9

what is the MoA of LMWH?

Answer 9

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

Question 10

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

Answer 10

unfractionated

Question 11

which type of heparin can be given at fixed doses?

Answer 11

LMWH

Question 12

what effect does heparin have on coagulation screen results?

Answer 12

PT and APTT will be prolonged

Question 13

what should be monitored when giving unfractionated heparin?

Answer 13

APTT

Question 14

what can be monitored to assess LMWH in complex patients?

Answer 14

anti-Xa assay

not usually needed

Question 15

what is the main risk of heparin use?

Answer 15

bleeding

Question 16

what is a possible rare complication of heparin?

Answer 16

heparin induced thrombocytopenia with thrombosis (HITT)

Question 17

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

Answer 17

FBC

Question 18

what causes HITT with heparin use?

Answer 18

when heparin results in antibody formation

Question 19

what complication can be caused by long term heparin use?

Answer 19

osteoporosis

Question 20

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

Answer 20

stop giving it

very short half life

Question 21

what can be given to reverse heparin in severe bleeding?

Answer 21

protamine sulphate

complete reversal for unfractionated, partial for LMWH

Question 22

name four coumarin anticoagulants

Answer 22

warfarin
phenindione
acenocoumarin
phenprocoumon

Question 23

what is the MoA of warfarin?

Answer 23

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

Question 24

what are the vitamin K dependent proteins involbed in haemostasis?

Answer 24

factors 2,7,9 and 10

protein C and S

Question 25

what should be given when starting on warfarin and why?

Answer 25

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

Question 26

when should patients take warfarin?

Answer 26

at the same time everyday

Question 27

how is warfarin response monitored?

Answer 27

INR

Question 28

what is the target INR for most patients on warfarin?

Answer 28

2-3

Question 29

what does a higher INR suggest?

Answer 29

less likely to thrombose, more likely to bleed

Question 30

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

Answer 30

omit warfarin doses

Question 31

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

Answer 31

administer oral vitamin K

Question 32

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

Answer 32

around six hours

Question 33

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

Answer 33

clotting factor concentrates

Question 34

what are the two types of DOACs?

Answer 34

oral direct thrombin inhibitors oral Xa inhibitors

Question 35

what monitoring is required for DOACs?

Answer 35

none

Question 36

name an oral direct thrombin inhibitor

Answer 36

dabigatran

Question 37

how do oral direct thrombin inhibitors work?

Answer 37

target thrombin, preventing the fibrin clot from forming also prevent factors 8+9 being activated

Question 38

when are direct thrombin inhibitors contraindicated and why?

Answer 38

patients with renal problems as they are renally excreted

Question 39

which type of DOAC is more commonly used?

Answer 39

oral Xa inhibitors

Question 40

how do oral Xa inhibitors work?

Answer 40

directly inhibit Xa

Question 41

name three oral Xa inhibitors

Answer 41

edoxaban rivaroxaban apixaban