Anticoagulants

Question 1

What does a prolonged prothrombin time indicate? Partial prothrombin?

Answer 1

Intrinsic pathway defect; Extrinsic pathway defect

Question 2

Discuss Warfarin (Coumadin)

Answer 2

Vitamin K antagonist

1. Inhibits factors 2,7,9, 10
2. Stops gamma-carboxylation reaction
3. Narrow therapeutic index
4. Requires frequent monitoring

Question 3

PKs of warfarin

Answer 3

1. Slow onset (4-5days)
2. Absorbed via GI
3. 99% bound to plasma albumin
4. Half-life of 44 hours

Question 4

Uses of warfarin

Answer 4

Tx for venous thrombosis, pulmonary/systemic embolism,

Question 5

Adverse effects of warfarin

Answer 5

1. Hemorrhage
2. Skin necrosis
3. Purple toe syndrome
4. Teratogenic

Question 6

How do you treat warfarin induced hemorrhage?

Answer 6

Rapid response: Fresh frozen plasma

Slow response: Vitamin K

Question 7

DDI of warfarin

Answer 7

Increase effects: alcohol, macrolides, Bactrim, Metronidazole, Fluoroquinolones

Question 8

Discuss Dabigatran

Answer 8

Competitive inhibitor of thrombin; prodrug activated by plasma esterase

Question 9

Discuss Idarucizumab

Answer 9

Antidote for Dabigatran; Monoclonal antibody

Question 10

Discuss Rivaroxaban and Apixiban

Answer 10

Oral direct inhibitors of Factor 10

Question 11

Discuss Heparin

Answer 11

A normally occuring antithrombin that regulates coagulation by inactivating factor 10 and thrombin irreversibly; Does not break clots, just prevents them

Question 12

Discuss Enoxaparin and dalteparin

Answer 12

Low molecular weight heparin; Greater effect on Factor 10 than on thrombin

Question 13

Why is protamine used?

Answer 13

Heparin antidote

Question 14

Why is Fondaparinux used?

Answer 14

Binds to antithrombin to increase its ability to inactivate Factor 10.