Anti-Coagulants

Question 1

What is the elimination order of heparin?

Answer 1

zero

Question 2

What is the benefit of orally active inhibitors?

Answer 2

predictable degree of anticoagulation

Question 3

What is the adverse side effect of anticoagulant drugs?

Answer 3

significant risk of haemorrhage

Question 4

How are low molecular weight heparins administered?

Answer 4

SC

Question 5

Why are low molecular weight heparins preferred to heparins?

Answer 5

no clotting test, except in renal failure - eliminated via renal excretion

Question 6

Give examples of low molecular weight heparins

Answer 6

enoxaparin, dalteparin

Question 7

What is thrombosis?

Answer 7

clot formed in the absence of bleeding

Question 8

What is the con of orally active inhibitors?

Answer 8

no specific agent to reduce haemorrhage in overdose

Question 9

Which orally active inhibitor inhibits factor Xa?

Answer 9

rivaroxaban

Question 10

Why does warfarin require monitoring?

Answer 10

low therapeutic index

Question 11

What increases the risk of thrombosis in patients who are taking warfarin?

Answer 11

pregnancy - increased clotting factor synthesis, hypothyroidism - decreased degradation of clotting factors, vitamin K consumption, drugs that increase the hepatic metabolism of warfarin

Question 12

What are the adverse effects of heparin and low molecular weight heparins?

Answer 12

haemorrhage, rare -osteoporosis, hypoaldersteronism, hypersensitivity reactions

Question 13

How is heparin administered?

Answer 13

IV - immediate onset, SC - onset delayed by an hour

Question 14

What orally active inhibitors inhibit thrombin?

Answer 14

dabigatran, etexilate

Question 15

How is the optimum dosage of heparin determined?

Answer 15

in vitro clotting test

Question 16

What is the mechanism of action of warfarin?

Answer 16

competes with vitamin K for binding to hepatic vitamin K reductase - renders factors II, VII, IX and X inactive

Question 17

Give examples of anti-coagulants

Answer 17

warfarin, heparin, low molecular weight heparins, orally active inhibitors

Question 18

What is the onset period for warfarin?

Answer 18

2-3 days - active factors cleared, heparin may be added for rapid effect

Question 19

What increases the risk of haemorrhage in patients who are taking warfarin?

Answer 19

liver disease - decrease clotting factors, high metabolic rate - increased clearance of clotting, drugs that inhibit hepatic metabolism of warfarin, drugs that inhibit platelet function - e.g. aspirin, NSAIDs, decreased availability of vitamin K

Question 20

How is warfarin administered?

Answer 20

oral

Question 21

What colour is a venous thrombosis?

Answer 21

red

Question 22

How are overdoses of warfarin treated?

Answer 22

vitamin K1 or IV concentrate of clotting factors

Question 23

What is a venous thrombosis made of?

Answer 23

fibrin rich

Question 24

Give examples of orally active inhibitors

Answer 24

dabigatran, etexilate, rivaroxaban

Question 25

What are orally active inhibitors used in?

Answer 25

prevent thrombosis in patients undergoing hip and knee replacements

Question 26

What are anti-coagulants used for?

Answer 26

deep vein thrombosis, prevention of post op thrombosis, patients with artificial heart valves, atrial fibrillation

Question 27

What is the elimination order of low molecular weight heparins?

Answer 27

first

Question 28

How is a haemorrhage caused by heparin or low molecular weight heparin treated?

Answer 28

discontinue drug - administer protamine sulfate IV

Question 29

Give an example of a drug that decreases the metabolism of warfarin

Answer 29

Amiodarone