Anticoagulants

Question 1

What are anticoagulant medicines?

Answer 1

• anticoagulants are medicines that help prevent blood clots
• generally thin the blood

Question 2

What was the first anticoagulant drug discovered, and the one we need to know?

Answer 2

• Warfarin

Question 3

What is the mechanism of action of Warfarin as an anti-coaggulant medication?

Answer 3

• inhibits vitamin K factors II (2), VII (7), IX 9 and X (10) - coagulation
• proteins S and C = anti-coagulation

Question 4

What is the mnemonic for remebering the mechanism of Warfarin?

Answer 4

• 1972 was the year of diSCo
• factors 9, 7, 2 and 10
• proteins S and C

Question 5

When administering Warfarin, it can initially making clotting worse, generally in the first 36 hours. Why is this the case?

Answer 5

• inhibits proteins S and C
• proteins S and C are anti-coaggulators

Question 6

Warfarin has a narrow therapuetic window and interacts with a number of factors including alcohol, green vegetables, P450 and antibiotics, making it a drug that is not commonly used. However, what 2 cases is Warfarin still used for?

Answer 6

• mechanical heart valves
• mitral valve stenosis with atrial fibrillation

Question 7

What are direct acting oral anticoagulants (DOACs)?

Answer 7

• drugs taken orally to reduce the risk of thrombosis (blood clot)

Question 8

Direct acting oral anticoaggulants (DOACs) are able to inhibit the coaggulation pathway and reduce the risk of thrombosis (blood clot). Which DOAC acts directly on the coaggulation cascade by inhibiting factor X (10)?

Answer 8

• Rivaroxaban

Question 9

Rivaroxaban is a drug that is able to inhibit factor X (10) in the coaggulation cascade. Why is factor X (10) so important in the coaggulation cascade?

Answer 9

• it sits between intrinsic and extrinsic pathways so powerful
• sits in the common pathway

Question 10

In the names of drugs that inhibit factor X (10) of the coagulation cascade there is a helpful way of identifying these drugs, what is it?

Answer 10

• they have XA in their name, which is factor XA (10a)
• RivaroXAban is an example

Question 11

Direct acting oral anticoaggulants (DOACs) are able to inhibit the coaggulation pathway and reduce the risk of thrombosis (blood clot). Which DOAC acts directly on the coaggulation cascade by inhibiting factor II (2), more commonly known as thrombin?

Answer 11

• Dabigatran

Question 12

Dabigatran is a DOAC drug that is able to inhibit factor II (2), more commonly known as thrombin. Why is thrombin important in the coaggulation cascade?

Answer 12

• thrombin converts fibrinogen to fibrin

Question 13

What is heparin?

Answer 13

• name heparin is because original heparin was found in liver
• anti-coaggulant medication

Question 14

What is the mechanism of action of heparin?

Answer 14

• anti-thrombin III is made and produced by the liver
• thrombin III inhibits aspects of the coagulation cascade
• heparin binds to anti-thrombin III and activates it

Question 15

Once heparin has bound to anti-thrombin III to inhibit the coagulation cascade it is able to inhibit a number of factors. What is an easy way to remember which aspects of the coagulation cascade heparin can inhibit?

Answer 15

• 2 + 7 = 9 then comes 10, 11, 12

Question 16

Heparin is a very effective drug, but the effects of the drug can vary depending on the batch. This is due to the high molecular weight of unfractioned heparin. What is fractionated and unfractionated heparin?

Answer 16

• unfractionated is physioloigical heparin and contains HMW and LMW heparin
• fractionated is processed heparin and contains only LMW heparin

Question 17

Is fractionated and unfractionated heparin used more commonly?

Answer 17

• fractionated

Question 18

What are the 2 fractionated heparin drugs that we need to know about?

Answer 18

• Enoxaparin and Tinzaparin
• both end in aparin

Question 19

Fractionated heparin is used more commonly more that unfractionated heparin due to efficacy and safety. But what is one of the main times when fractionated low molecular weight heparins are not used?

Answer 19

• needs to be cleared by the kidneys
• if patient has significant renal impariment