Antithrombotic Agents/Coagulation Flashcards

1
Q

What triggers intrinsic clotting cascade? What factors are involved in Intrinsic cascade?

A

Endothelial damage. 12, 11, 9, 10

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2
Q

What triggers extrinsic clotting cascade? What factors are involved?

A

Vessel/extravascular tissue damage. 7, 10

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3
Q

What factors are common to both pathways?

A

Xa, 5a (converts prothrombin to thrombin)

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4
Q

What are inhibitors of clotting cascade?

A

Protein C/S (inhibit 8 and 5), Tissue factor pathway inhibitor (inhibits 7A-TF complex), Antithrombin III (inhibits protease, 10, 2)

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5
Q

How long do platelets circulate? What kind of thrombi are they found in?

A

7-10 days. Arterial only (not venous)

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6
Q

What’s MOA of aspirin? What effect does it have on CV dz?

A

Irreversible COX1 inhibitor at low dose, COX2 inhibitor at high dose (>1g/day). 25% mortality reduction from CV

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7
Q

What’s MOA of dipyridamole? When is it used?

A

inhibit PDA and adenosine deaminase->decrease plt aggregation/thrombosis. VTE ppx after valve replacement with coumadin 75-100 mg QID

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8
Q

What’s MOA of cilostazol? What are contraindications? How long do you take it for claudication?

A

PDE3 inhibitor -> decrease smooth muscle contractility, inhibit plt aggregation. Avoid grapefruit, CI in heart failure. 6-12 weeks to see effectiveness

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9
Q

How do P2Y12 inhibitors work? What’s score for PRU?

A

Inhibit P2Y12 -> inhibit ADP binding -> unable to stimulate platelet aggregation. PRU>235 indicates high likelihood of resistance

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10
Q

How is clopidogrel activated?

A

Metabolized/activated by hepatic CYP 2C19

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11
Q

What’s dose of Prasugrel?

A

Loading 60 mg, maintenance 10 mg daily (5 mg daily if <60kg)

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12
Q

What’s different about mechanism of Ticagrelor? What’s dose?

A

Binds P2Y12 but not at the ADP binding site. Loading 180 mg, 90 mg BID x 1y then 60 mg BID

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13
Q

What’s an IV P2Y12 inhibitor? What’s dose?

A

Cangrelor. Loading: 30 mcg/kg IV bolus, Maintenance: 4 mcg/kg/min.

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14
Q

What’s MOA of Tirofiban? What’s dose?

A

Reversible competitive inhibitor of GP IIb/IIIA receptor. Loading 25 mcg/kg IV, infusion 0.15 mcg/kg/min

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15
Q

What’s MOA of Eptifibatide? What’s dose?

A

Blocks fibrinogen/vWF binding to GP IIb/IIIA on platelet surface. 180 mg/kc IV bolus, maintenance 2 mcg/kg/min

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16
Q

What’s dose of heparin for VTE treatment?

A

80 units/kg bolus then 18 units/kg/hr

17
Q

How does antithombin III deficiency present? How do you get heparin to work?

A

VTE (not arterial), inability to achieve therapeutic ACT despite heparin administration (give direct thrombin inhibitors). Administer 2u FFP immediately after heparin to provide antithrombin III for heparin to work

18
Q

How does protamine work? How is it dosed?

A

Combines with heparin to form neurtalized salt. 1 mg protamine for 100 units of heparin

19
Q

How does enoxaparin work?

A

Binds/potentiates antithrombin to inactivate factor Xa.

20
Q

How does fondaprinux work?

A

bind antithormbin, does not inhibit thrombin

21
Q

What are direct thrombin inhibitors? What are reversal agents?

A

Bivalirudin, argatroban, dabigatran. PCC, Idarucizumab for dabigatran

22
Q

How does warfarin work?

A

Inhibit vitamin K epoxide reductase > inhibit synthesis of factor 2, 7, 9, 10, protein C/S

23
Q

What are reversal agent for apixaban/rivaroxaban?

A

Recombinant factor xa (andexanet alfa)

24
Q

What pathways are measured by PT and PTT?

A

PT: Extrinsic, PTT: intrinsic

25
Q

What are components of FFP, CPP, PCC?

A

FFP: all factors except 8
CPP: 8, vWF, Fibrinogen
PCC: 2, 7, 9, 10