Anticoagulant Drugs

Question 1

What are the 2 forms of Heparin?

Answer 1

Unfractioned and Low molecular weight (LMWH)

Question 2

What does Heparin act on to bring about it’s therapeutic effect?

Answer 2

Anti-thrombin
(It Potentiates Antithrombin which is a naturally occuring anticoagulant)

Question 3

How is unfractioned monitored?

Answer 3

Activated partial thromboplastin time (APTT)

Question 4

How is LMWH monitored?

Answer 4

Anti-Xa assay,
However there is not usually any monitoring of LMWH required as it’s more predictable.

Question 5

What are the potential complications of Heparin?

Answer 5

• Bleeding.
• Heparin induced Thrombocytopenia (HITT).
• Osteoporosis with long term use.

Question 6

How is the risk of Heparin Induced Thrombocytopenia (HITT) monitored?

Answer 6

Monitoring FBC in patients on Heparin.

Question 7

What is the Reversal Protocol for Heparin?

Answer 7

Stop the heparin (it has a short half life).

Occasionally in severe bleeding,
- Protamine sulphate. Reverses antithrombin effect.
Complete reversal required for unfractioned. Partial reversal for LMWH.

Question 8

What are examples of Coumarin Anticoagulants?

Answer 8

Warfarin, Phenindione, Acenocoumarin, Phenprocoumon.

Question 9

What are the mechanisms of action of coumarins?

Answer 9

Inhibition of Vitamin K

Question 10

Vitamin K is the final Carboxylation of clotting factors…?

Answer 10

Factors 2 (thrombin) , 7, 9 and 10.
Gives platelets their negative charge.

Question 11

What are proteins C and S?

Answer 11

Protein C and protein S are two important natural anticoagulants in the body that play a role in regulating blood clot formation.

Question 12

Where are Protein C and S synthesised and what vitamin do they Require?

Answer 12

in the liver - They Require vitamin K for final carboxylation step essential for function.

Question 13

How does warfarin act in the liver?

Answer 13

Acts as an anticoagulant by blocking the ability of Vitamin K to carboxylate the Vit.K dependent clotting factors, thereby reducing their coagulant activity.

Question 14

How would Acute thrombosis be treated in hospital with anticoagulants?

Answer 14

Rapid initiation of Warfarin and Heparin (heparin works while warfarin gets up to therapeutic effect)

Question 15

What test is used to monitor Warfarin?

Answer 15

Prothrombin Time.
(INR calculated and used)

Question 16

What are the major potential complications of Warfarin?

Answer 16

Haemorrhage (major adverse effect)

Mild - Skin bruising, Epistaxis, Haematuria.

Severe - GI bleed, Intracerebral, Significant drop in Hb.

Question 17

What factors influence the reversal of Warfarin requirement?

Answer 17

Depends on severity of bleeding and INR.

Question 18

What is the speed of action of Vitamin K in Warfarin reversal?

Answer 18

6 hrs.

Question 19

What is the stepwise process of reversal of Warfarin?

Answer 19

Omit warfarin Dose,
Administer oral Vit K,
Administer clotting factors (factor concentrates),
Monitor response.

Question 20

What are the 2 types of New Anticoagulants?

Answer 20

Direct Thrombin inhibitors (Dabigatran). - ((Used rarely))

Direct activated factor X inhibitors. (Edoxaban, Rivaroxaban, Apixaban)