Anticoagulant drugs

Question 1

indications for anticoagulant drugs

Answer 1

VTE recurrent
AF
valve replacement

Question 2

action of heparin

Answer 2

potentiates antithrombin by making the antithrombin-thrombin complex stronger
also acts on factor Xa

Question 3

what are the 2 types of heparin

Answer 3

unfractionated

low molecular weight

Question 4

when is heparin used

Answer 4

acute VTE (DVT, PE)

Question 5

route for heparin

Answer 5

IV/SC

Question 6

what does unfractionated mostly affect

Answer 6

thrombin

Question 7

what does LMW mostly affect

Answer 7

factor Xa

Question 8

what type of heparin requires monitoring

Answer 8

unfractionated

Question 9

how is unfractionated heparin monitored

Answer 9

APTT

Question 10

how often does APTT need to be checked in unfractionated heparin use

Answer 10

every 4-6 hours

Question 11

why would unfractionated be used over LMWH

Answer 11

risk of bleeding eg GI ulcers

Question 12

when is heparin used long term

Answer 12

prophylaxis in pregnancy if at high risk

warfarin is contraindicated in pregnancy

Question 13

complications of heparin

Answer 13

bleeding
thrombocytopenia (monitor FBC, patient collapses within 5-10 days of onset)
osteoporosis if long term

Question 14

how is heparin reversed

Answer 14

stop heparin (half life of half an hour)

Question 15

if severe bleeding in heparin therapy, what is management and how effective is it

Answer 15

protamine sulfate
complete reversal if unfractionated
partial reversal if LMWH

Question 16

what are coumans

Answer 16

warfarin

phenindione

Question 17

action of warfarin

Answer 17

inhibits vitamin K which is required to decarboxylate factors 2, 7, 9 and 10 to make them active
warfarin keeps them inactive

Question 18

what else is vitamin K required for

Answer 18

protein C and S function

Question 19

during initiation of warfarin, what else should be given and why

Answer 19

heparin

proteins C and S are first to be affected by warfarin - become more thrombotic in first few days

Question 20

when should warfarin be taken

Answer 20

same time every day (6pm I recommended)

Question 21

what is warfarin metabolised by and why is this important clinically

Answer 21

cytochrome P450b enzymes
antibiotics are also metabolised this way - less warfarin metabolised
higher warfarin conc = higher chance of bleed

Question 22

how is warfarin monitored and what is the target

Answer 22

using INR

2-3 (higher for mechanical valves)

Question 23

what are minor bleeds

Answer 23

epistaxis
haematuria
bruising

Question 24

what are major bleeds

Answer 24

GI bleeds
intracerebral bleeds
if drop in BP

Question 25

INR 4.5-6 and no bled

Answer 25

reduce warfarin dose

Question 26

INR 6-8

Answer 26

stop warfarin | resume when <5

Question 27

INR >8 with no bleed/minor bleed

Answer 27

stop warfarin | give vit K

Question 28

how long does Vit K take to work

Answer 28

6 hours

Question 29

if INR >8 and major bleed

Answer 29

stop warfarin give beriplex (contains clotting factors) Vit K fresh frozen plasma if required

Question 30

how often is INR checked

Answer 30

every day on initiation then alternative days then weekly

Question 31

signs of warfarin toxicity/overdose (SAFETY NETTING)

Answer 31

``` blood in stool haemoptysis heavy periods blood in urine hameatemasis/abdo pain purpura/bruising bleeding from cuts nose bleeds swollen joints/joint pain dizziness vision changes ```

Question 32

how are patients bleeding risk assessed

Answer 32

``` HASBLED score H - hypertension >160 A - abnormal renal or liver function S - stroke history B - bleeding disposition L - labile INR E - elderly D - drinks >8 alcohol drinks /week, other antibleeding drugs >3 points = high risk of bleeding ```

Question 33

example of thrombin inhibitor

Answer 33

dabigatran

Question 34

examples of factor Xa inhibitors

Answer 34

rivaroxaban | apixapan

Question 35

advantages of new anticoagulants

Answer 35

oral no monitoring required less drug interactions

Question 36

disadvantage with new anticoagulants

Answer 36

no antidote