Hematological agents I

Question 1

what allows fibrin to remain at the site of injury?

Answer 1

when bound to thrombin it cannot be inhibited by antithrombin / heparin

Question 2

what are features of venous thrombi?

Answer 2

1. platelet poor - “red thrombi”
2. often occur at valves
3. antiplatelet therapy not usually useful

Question 3

what are features of arterial thrombi?

Answer 3

1. platelet rich - “white thrombi”

2. occur atop plaque ruptures

Question 4

what is the MOA of aspirin?

Answer 4

1. irreversible inhibition of COX-1 in platelets

2. reduces TXA2 production - reduction in platelet activation and aggregation

Question 5

what class of drug is dipyridamole? what is the MOA?

Answer 5

1. antiplatelet
2. inhibits phosphodiesterase
3. more cAMP, less calcium (in platelets), less activation

Question 6

what is the role of P2Y12?

Answer 6

1. ADP receptor

2. binding leads to platelet activation

Question 7

what class of drug are clopridogrel and prasugrel? what is the MOA?

Answer 7

1. antiplatelet
2. irreversible P2Y12 inhibitors - decrease GpIIb/IIIa
3. must be activated by liver

Question 8

what class of drug are ticagrelor and cangrelor? what is the MOA?

Answer 8

1. antiplatelet
2. irreversible P2Y12 inhibitors - decrease GpIIb/IIIa
3. does NOT need to be metabolized by liver

Question 9

prasugrel and ticagrelor are not recommended in patients with what history?

Answer 9

intracranial bleeding

Question 10

what are the GpIIb/IIIa antagonists? what is the MOA?

Answer 10

1. abciximab
2. eptifibatide
3. tirofiban

Question 11

what is the MOA of abciximab?

Answer 11

1. fragment of monoclonal against GpIIb/IIIa

2. prevents fibrinogen cross bridges between platelets

Question 12

what class of drug is vorapaxar? what is the MOA?

Answer 12

1. protease activated receptor (PAR) antagonist

2. blocks thrombin - does not allow to bind to GPCR

Question 13

what are the indirect thrombin inhibitors (bind to antithrombin)?

Answer 13

1. heparin
2. enoxaparin
3. fondaparinux

Question 14

what are the direct thrombin inhibitors?

Answer 14

1. lepirudin
2. bivalirudin
3. argatroban
4. dabigatran

Question 15

what are the direct Xa inhibitors?

Answer 15

1. rivaroxaban

2. apixaban

Question 16

how does heparin work?

Answer 16

binds antithrombin at endothelial surface, increases inhibition of factor Xa thrombin

Question 17

how is unfractionated heparin different from regular heparin?

Answer 17

unfractionated heparin is shorter and cannot keep thrombin in close proximity - can only activate antithrombin and have effects on Xa inactivation

Question 18

what are the two mechanisms of heparin clearance?

Answer 18

1. rapid but saturable by endothelial cells

2. non-saturable via kidney and liver

Question 19

what is the main test for heparin monitoring?

Answer 19

activated partial thromboplastin time (aPTT)

Question 20

in instances of severe bleeding, what agent can be used to inactivate heparin?

Answer 20

protamine