Anticoagulant drugs

Question 1

anticoagulants are used for arterial/venous thrombosis

Answer 1

venous

Question 2

what are the main indications for anticoagulants

Answer 2

DVT

atrial fibrillation

Question 3

venous clots are platelet/fibrin rich

Answer 3

fibrin

Question 4

what types of anticoagulants are there

Answer 4

heparin
warfarin
DOACs

Question 5

how does heparin work

Answer 5

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

Question 6

heparin has an immediate/delayed effect

Answer 6

immediately effective

Question 7

the therapeutic index of heparin and warfarin are wide/narrow

Answer 7

narrow

Question 8

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

Answer 8

thrombin

Question 9

when LMWH binds to antithrombin it enhances

thrombin/Xa inhibition more

Answer 9

Xa

Question 10

how is unfractionated heparin administered

Answer 10

IV

Question 11

how is LMWH administered

Answer 11

SC

Question 12

which needs more monitoring, unfractionated heparin or LMWH

Answer 12

unfractionated heparin

Question 13

how do you monitor unfractionated heparin

Answer 13

APTT

Question 14

how can you monitor LMWH

Answer 14

anti-Xa assays

Question 15

why is APTT measured for heparin

Answer 15

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

Question 16

what are complications of heparin

Answer 16

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

Question 17

how do you reverse heparin

Answer 17

stop heparin

if severe bleeding:
protamine sulphate

Question 18

heparin has a short/long half life

Answer 18

short

Question 19

what is the antidote to heparin overdose

Answer 19

protamine sulphate

Question 20

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

Answer 20

Coumarin anticoagulant group

Vit K antagonists

Question 21

Vit K is fat/water soluble

Answer 21

fat

Question 22

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

Answer 22

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

Question 23

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

Answer 23

this allows clotting factors to effectively bind to platelet plug

Question 24

When you start warfarin, levels of which proteins go down

What is a consequence of this

Answer 24

Protein C+S

causes you to become prothrombotic initially

Question 25

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

Answer 25

heparin | because of increased thrombosis risk initially

Question 26

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

Answer 26

Cytochrome P450

Question 27

how is warfarin monitored

Answer 27

INR internationalised normalised ratio standardised across the world

Question 28

what is the ideal target INR

Answer 28

2-3

Question 29

what are complications of warfarin therapy

Answer 29

bleeding co-morbidities DRUG INTERACTIONS

Question 30

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

Answer 30

INR

Question 31

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

Answer 31

omit doses of warfarin

Question 32

what can you give to quickly reduce INR

Answer 32

PO vitamin K

Question 33

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

Answer 33

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

Question 34

how fast do Vit K and clotting factors work

Answer 34

vit K - 6 hours | clotting factors - immediately

Question 35

indications for warfarin

Answer 35

metal heart valves | APLS

Question 36

what are DOACs

Answer 36

Direct oral anticoagulants | newer agents that directly target Xa or thrombin

Question 37

how are DOACs administered

Answer 37

PO

Question 38

why are DOACs more favourable to use

Answer 38

no monitoring required | less drug interactions

Question 39

give an example of a direct thrombin inhibitor

Answer 39

dabigatran

Question 40

what is the method of action of dabigatran

Answer 40

inhibits thrombin which means fibrin cannot form from fibrinogen

Question 41

where is dabigatran metabolised and excreted

Answer 41

kidneys

Question 42

give examples of direct Xa inhibitors

Answer 42

rivaroxiban, apixaban, edoxiban

Question 43

how does rivaroxiban work

Answer 43

inhibits factor Xa and so prevents thrombin formation

Question 44

indications for DOACs

Answer 44

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

Question 45

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

Answer 45

liver disease/cirrhosis high metabolic activity drug interactions Bleeding risk

Question 46

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

Answer 46

Pregnancy hypothyroidism Vitamin K consumption drug interactions clot formation