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Pharm 2 > Antiplatelet Medications > Flashcards

Antiplatelet Medications Flashcards

1
Q

What are the 3 functions of platelets?

A
  • activation
  • adhesion
  • aggregation
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2
Q

Which clotting factors promote platelet adhesion to damaged vascular walls?

A
  • factor VIII and vWF
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3
Q

What is the most common inherited coagulation defect?

A
  • vonWillebrand’s disease
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4
Q

What factor activates the platelet?

A
  • thrombin (factor IIa)
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5
Q

What 2 mediators promote platelet aggregation?

A
  • ADP
  • thromboxane A2

They uncover the fibrinogen receptor, which links PLT’s together

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6
Q

What clotting factor causes platelet aggregation?

A
  • fibrinogen (factor I)

- attaches to receptors and links platelets together

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7
Q

What are the 4 types of platelet aggregation inhibitors?

A
  • aspirin
  • NSAIDS
  • platelet glycoprotein (GP IIb/IIIa) receptor inhibitors
  • thienopyridine ADP-receptor antagonists
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8
Q

Name 4 thienopyridine ADP-receptor antagonists

A
  • clopidogrel (Plavix)
  • prasugrel (Effient)
  • ticagrelor (Brilinta)
  • ticlopidyne (Ticlid)
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9
Q

What is the mechanism of action of thienopyridine ADP-receptor antagonists?

A
  • bind selectively and non-competitively to low affinity ADP receptor binding site on surface of platelets
  • causes inhibition of ADP binding to the receptor and inhibits activation of platelet glycoprotein complex necessary for fibrinogen platelet binding
  • receptor is irreversibly modified by these drugs
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10
Q

How long should plavix be stopped prior to surgery?

A
  • 7 days

- platelet aggregation and bleeding time return to baseline values within 5 days

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11
Q

True or False

Platelets exposed to Plavix or Effient are affected for the remainder of their lifespan.

A
  • true
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12
Q

How long does it take for plavix to reach a steady state in the blood?

A
  • 40-60% inhibition after the first day of therapy

- steady state reached in 3-7 days

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13
Q

What medication can normalize prolonged bleeding time within 2 hours in patients being treated with ticlid?

A
  • methylprednisolone

- platelet transfusion can also be used to reverse the effects (avoid in patients with TTP).

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14
Q

When should ticagrelor (Brilinta) be stopped prior to surgery?

A
  • 5 days
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15
Q

When should prasugrel (Effient) be stopped prior to surgery?

A
  • 7 days
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16
Q

True or False

Brilinta is not reversible.

A
  • false
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17
Q

Brilinta is a __________ substrate.

A
  • CYP3A4
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18
Q

How long will it take for a patient to return to baseline after Effient is discontinued?

A
  • 5-9 days
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19
Q

How long does it take for Effient to reach steady state in the body?

A
  • half of platelets are inhibited within 1 hour

- steady state in 3-5 days

20
Q

What are the adverse effects of plavix, Effient and Brilinta?

A
  • bleeding
  • diarrhea
  • N/V
  • rash
  • thrombotic thrombocytopenia purpura
  • severe neutropenia
21
Q

What are the adverse effects of Ticlid?

A
  • greater than 50% of patients have diarrhea or rash
  • agranulocytosis
  • aplastic anemia
  • bleeding
  • severe neutropenia
  • thrombotic thrombocytopenia purpura
22
Q

True or False

Cangrelor (Kengreal), a platelet aggregation inhibitor, should not be administered with a GIIb/IIIa inhibitor.

A
  • true
23
Q

What is measured by VerifyNow P2Y12?

A
  • measures the percentage of platelet inhibition
  • used to monitor antiplatelet therapy
  • can be used to help determine when it is safe to proceed with surgery or regional anesthesia (<20% inhibition)
24
Q

What are 3 assays that can be used to measure platelet inhibition?

A
  • VerifyNow aspirin
  • VerifyNow IIb/IIIa
  • VerifyNow P2Y12
25
Q

What is the mechanism of action of platelet glycoprotein IIb/IIIa receptor inhibitors?

A
  • interact with platelet glycoprotein IIb/IIIa to inhibit fibrinogen binding to activated platelets
  • leads to inhibition of platelet aggregation and clot retraction
26
Q

What are indications for use of platelet glycoprotein IIb/IIIa receptor inhibitors?

A
  • acute ischemic complications of percutaneous coronary intervention
  • unable angina
  • non Q-wave MI
27
Q

What are adverse effects associated with platelet glycoprotein IIb/IIIa receptor inhibitors?

A
  • anaphylaxis
  • bleeding
  • hypotension
  • N/V
  • thrombocytopenia
28
Q

What GI med can cause stent failure if given with plavix?

A

Prilosec

plavix is a prodrug. If you give a CYP2C9 it inhibits the prodrug activation. Prilosec is a 2C9

29
Q

What is the only ADP receptor antagonist that is reversible?

A

ticagrelor (Brilinta)

30
Q

vonWillebrand’s factor (Factor VIII:vWF) is manufactured and released from _______

A

endothelial cells

31
Q

MOA of aspirin

A

Renders cyclooxygenase nonfunctional for the life of the PLT (8-12 days)

32
Q

MOA of NSAID’s

A

Depression of thromboxane-A2 production by platelets is only temporary (approx. 24-48 hours).

33
Q

What is cyclooxygenase?

A

Rate-limiting enzyme in the conversion of arachidonic acid to thromboxane-A2

Without thromboxane-A2, platelet aggregation is impaired

34
Q

What is the most widely used ADP receptor antagonist?

A

Plavix

35
Q

Name 3 platelet GIIb/IIIa receptor inhibitors

A

Abciximab (ReoPro®)
Eptifibatide (Integrilin ®)
Tirofiban (Aggrastat ®)

These work OUTSIDE of the platelet

36
Q

T/F

With the exception of Ticagrelor (Brilinta®), all other ADP receptor antagonists are irreversible

A

True

37
Q

ADP receptors antagonists are ____, _____, _____

A

selective
noncompetitive
irreversible

38
Q

Which ADP receptor inhibitor has the longest hold time prior to surgery?

A

Ticlopidine (Ticlid ®) Needs to be held 14 days

39
Q

What can be done to reverse ADP inhibitors

A

basically just give PLT’s and blood products

40
Q

What is the only IV P2Y12 inhibitor?

A

Cangrelor

41
Q

Is cangrelor reversible?

A

yes, PLT’s return to normal after 1 HOUR of stopping infusion

42
Q

With VerifyNow, it safe to proceed with surgery or regional anesthesia if PLT inhibition is ____

A

less than 20%

43
Q

What anti-platelet med is not effective when used alone, only when combine with an anticoagulant or PLT aggreagation inhibitor?

A

Dipyridamole (Persantine®)

44
Q

What med is a combination of dipyridamole and ASA?

A

Aggrenox

Used in CVA patients

45
Q

what is the major drawback to Vorapaxar (Zontivity ®)?

A

Long half life of 5-13 days

46
Q

Which GIIb/IIIA antagonist is not rapidly reversible?

A

Abciximab (Reopro)

All of them are reversible, this med just takes longer (48hrs)

Emily stressed in the lecture that this is the important thing to know about GIIb/IIIa inhibitors

47
Q

T/F

SQ Heparin is a contraindication to the use of neuraxial techniques

A

FALSE

If on heparin > days, just check PLT count first to r/o HIT

Pharm 2 (19 decks)

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