Anticoagulants

Question 1

What are the common indications for anticoagulation?

Answer 1

venous thrombosis; atrial fibrillation

Question 2

How are protein C and S activated?

Answer 2

by thrombin bound to thrombomodulin

Question 3

What is the mechanism of heparin?

Answer 3

potentiates antithrombin by stabilising anti-thrombin:protein complex

Question 4

how is heparin administered?

Answer 4

parenteral (IV/SC)

Question 5

What are the 2 forms of heparin?

Answer 5

unfractionated and LMWH

Question 6

What are the mechanisms of anti-thrombin?

Answer 6

inhibts fibrinogen–fibrin and amplification steps

Question 7

What protein is bound to anti-thrombin in the complex that unfractionated heparin works on?

Answer 7

thrombin

Question 8

What is the protein bound to anti-thrombin that LMWH works on?

Answer 8

Xa

Question 9

How is unfractionated heparin monitored?

Answer 9

APTT

Question 10

How is LMWH monitored?

Answer 10

anti-Xa assayu

Question 11

What is the aim for the change to APTT in heparin?

Answer 11

1.5-2x normal

Question 12

Why is monitoring of LMWH not required?

Answer 12

much more predictive dosing- based on weight, whereas unfractionated isn’t so predictable

Question 13

What are the complications of heparin thepray?

Answer 13

bleeding; heparin induced thrombocytopenia (with thrombosis); osteoporosis

Question 14

What bloods should be monitored in patients on heparin?

Answer 14

FBC

Question 15

What causes heparin induced thrombocytopenia?

Answer 15

develop antibody to platelet factor IV which causes platelets to stick together

Question 16

Which form of heparin is HITT more likely in?

Answer 16

unfractionated

Question 17

What is the anti-dote to heparin?

Answer 17

protamine sulphate

Question 18

Give two examples of coumarin anticoagulants?

Answer 18

warfarin; phenindione

Question 19

What is the mechanism of coumarin anticoagulants?

Answer 19

inhibition of vitamin K

Question 20

What are the vitamin k dependent factors?

Answer 20

II; VII; IX and X; protein C and S

Question 21

What is the function of the carboxylation by vitamin K?

Answer 21

need second carboxyl group to makr chemical bond strong enough

Question 22

How is warfarin metabolised?

Answer 22

cytochrome P450

Question 23

How should warfarin be taken?

Answer 23

at same time every day (6pm recommended)

Question 24

Why does warfarin therapy need to be monitored?

Answer 24

narrow therapeutic window

Question 25

What is the equation for INR?

Answer 25

(patients PT/mean normal PT)^ISI

Question 26

What is the ISI?

Answer 26

callibration factors as thromboplastin can be different across labs

Question 27

What is generalyl the target INR?

Answer 27

2-3

Question 28

What are the factors that influence bleeding risk on warfarin?

Answer 28

intensity of anticoagulation; comrobidities; drug interactions

Question 29

What should be done with a patient on warfarin if any other medications are changed?

Answer 29

check INR

Question 30

What is the mnemonic for drugs that potentiate warfarin?

Answer 30

O! DEVICES

Question 31

What does O! dEVICES stand for?

Answer 31

``` Omeprazole Disulfriam Erythromycin Valproate Isoniazide Ciprfloxacin and cimetidine Ethanol (acute) Sulphonamides ```

Question 32

What is the mnemonic for drugs that inhibt warfarin?

Answer 32

PC BRAS

Question 33

What does PC BRAS stand for | ?

Answer 33

``` Phenytoin Carbamazepine Barbiturates Rifampicin Alcohol (chronic) Sulfonylureas ```

Question 34

How long does vitamin K take to work?

Answer 34

6 hours

Question 35

How long does a clotting factor transfusion take to work?

Answer 35

immediate

Question 36

What is the main new thrombin inhibitor?

Answer 36

dabigatram

Question 37

What is the difference between the new and old anticoagulants?

Answer 37

new agents bind directly to the coagulation factors

Question 38

What new agents are Xa inhibitors?

Answer 38

rivaroxaban; apixaban

Question 39

What are the benefits of the new anticoagulation agents?

Answer 39

oral and no monitoring; less interactions

Question 40

What is the con of the new anticoagulants?

Answer 40

no specfic antidote