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CVPR: CV Unit II > Anticoagulant & Antiplatet Drugs > Flashcards

Anticoagulant & Antiplatet Drugs Flashcards

1
Q

General characteristics of normal thrombus formation

A
  1. exposure of circulating blood elements to thrombogenic material (e.g. unmasked sub-endothelial collagen after plaque rupture)
  2. activation and aggregation of platelets
  3. triggering of the coagulation cascade –> fibrin clot formation
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2
Q

Intrinsic pathway summary and common drug targets

A
  • Factor XIIa -> XIa -> IXa + VIII -> Xa.
  • Heparin inactivates: XIIa, XIa, IXa, Xa
  • Warfarin inhibits synthesis: IX, X
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3
Q

Extrinsic pathway summary and common drug targets

A
  • tissue factor + VIIa -> Xa.
  • Heparin inactivates: VIIa
  • Warfarin inhibits synthesis: VII
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4
Q

Common pathway summary and common drug targets

A

Common: Xa + Va –> IIa (Thrombin) -> Ia (Fibrin) + XIII -> clot.

  • Heparin inactivates: Xa, Thrombin (IIa)
  • Warfarin inhibits synthesis: X, Prothrombin (II)
  • Rivaroxaban & LMWH-ATIII/Fondaparinux inhibit: Xa
  • Dabigatran & Hirudin/Bivalirudin inhibit: Thrombin
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5
Q

Thrombin inhibitors

A
  • Dabigatran
  • Hirudin/Bivalirudin
  • Warfarin
  • Heparin
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6
Q

Factor Xa inhibitors

A
  • Rivaroxaban
  • LMWH-ATIII/Fondaparinux
  • Warfarin
  • Heparin
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7
Q

Coagulation cascade summary/drug targets (diagram)

A

[picture}

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8
Q

Examples of anticoagulant drugs

A
  • Heparin
  • low MW heparins [enoxaparin]
  • warfarin
  • dabigatran
  • rivaroxaban
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9
Q

Examples of thrombolytic agents

A
  • streptokinase

- tissue plasminogen activator and variants

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10
Q

Examples of antiplatet agents

A
  • Aspirin
  • clopidrogel
  • dipyridamole
  • abciximab/epifibatide/tirofiban
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11
Q

Venous vs. aterial thrombi

A
  • venous = composed mainly of fibrin and trapped red blood cells with relatively few platelets
  • arterial = composed mainly of platelet aggregates held together by small amounts of fibrin
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12
Q

Anticoagulant agents general characteristics

A
  • prevention and treatment of venous thromboembolism
  • prevention of cardioembolic events in patients with atrial fibrillation
  • also effective for arterial thrombosis and their effects can be additive with antiplatelet agents
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13
Q

Antiplatet agents general characteristics

A
  • primarily for prevention and treatment of arterial thrombosis
  • primary and secondary prevention and treatment of acute coronary syndrome
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14
Q

General mechanisms of blood coagulation

A
  1. emerging blood increases mechanical pressure and helps limit blood loss; vessel damage exposes collagen of subendothelium
  2. vessels constrict
  3. platelets adhere
  4. platelets activate
  5. blood coagulates via coagulation cascade
  6. blood flow returns to normal
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15
Q

Warfarin inhibits:

A
  • vit K factors:
  • II
  • VII
  • IX
  • X
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16
Q

Heparin inactivates:

A
  • w/antithrombin III (ATIII):
  • IIa
  • IXa
  • Xa
  • XIa
  • XIIa
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17
Q

Low molecular weight heaparins (LMWH)/Fondaparinux inactivates

A
  • w/ATIII:

- Xa

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18
Q

Hirudin, Dabigatran inactivates

A

-directly inactivates IIa (thrombin)

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19
Q

Rivaroban inactivates:

A

-directly inactivates Xa

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20
Q

PT test

A
  • tests extrinsic pathway –> prolonged = defect @ extrinsic
  • used to monitor oral (warfarin) anticoag therapy
  • INR=patient PT/mean normal PT –> allows comparison between labs
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21
Q

aPTT test characteristics

A
  • tests intrinsic pathway –> prolonged = defect @ intrinsic
  • used to monitor heparin therapy
  • not significantly affected by LMWH
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22
Q

Ecarin Clotting Time (ECT)

A

-monitors therapy w/direct thrombin (IIa) inhibitors = hirudin & dabigatran

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23
Q

Factors that normally limit clot formation

A
  • prostacyclin (PGI2) and nitrous oxide=vasodilate and inhibit platelet agg.
  • Antithrombin III & Protein C/Protein S
  • fibrinolysis via plasmin
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24
Q

Fibrin inhibition mechanisms

A

-Antithrombin: protease inhibitor that inactivates IIa, IXa, Xa, XIIa less activated of X

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25
Q

Heparin: MOA

A
  • inhibits activated clotting factors
  • accelerates ATIII activity –> inhibits clotting factors
  • inhibits: IIa (thrombin), IXa, Xa, XIa, XIIa, XIIIa
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26
Q

Heparin: Pharmacokinetics

A
  • IV or SC
  • loading dose needed for anticoagulant effect
  • continuous infusion preferred for heparin
  • renal elimination
  • safe in pregnancy
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27
Q

Heparin: Uses

A
  • treatment of coronary occlusion in unstable angina/acute MI
  • prophylaxis tx of venous thromboembolism (VTE)
  • prevent cerebral thrombosis in stroke
  • prophylaxis tx for post-op thromboembolism
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28
Q

Heparin: Adverse Rxns

A
  • bleeding risk
  • hypersensitivity
  • thrombocytopenia: mild or severe (immune-mediated)
  • osteoporosis
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29
Q

Parenteral anticoagulants

A

-heparin
-LMWH (Enoxapirin)
-Fondaparinux
Direct thrombin (IIa) inhibitors

30
Q

LMWH: drug example

A

-Enoxapirin

31
Q

LMWH: MOA

A

-Binds to ATIII to inactivate factor Xa, but not IIa (thrombin)

32
Q

LMWH: Pharmacokinetics

A
  • IV or SC
  • longer t1/2
  • first-order renal elimination
  • safe in pregnancy
33
Q

LMWH: Uses

A
  • equal efficacy as regular heparin for VTE
  • less bleeding complications & thrombocytopenia
  • PTT not affected –> no monitoring needed
34
Q

LMWH: Overdose sx/signs and tx

A
  • bleeding is chief sign nosebleed, hematuria, bruising

- tx: protamine –> neutralizes hepearin w/in 5 min

35
Q

Warfarin: MOA

A
  • Acts in liver to prevent synthesis of clotting factors
  • Blocks vit-K dependent factors (II, VII, IX, X)
  • Increases prothrombin time
36
Q

Warfarin: Pharmacokinetics

A
  • Oral
  • Onset delayed until turnover of existing clotting factors
  • Reaches max effect @ 3-5 days
  • Metabolized by CYP2C9
  • Genetic polymorphisms
37
Q

Warfarin:Uses

A
  • Afib: prevent thromboembolic complications

* Prophylaxis/treatment of vneous thromboembolism

38
Q

Warfarin: Adverse Rxns

A
  • Hemorrhage
  • GI upset
  • Contraindicated in pregnancy
39
Q

Warfarin: overdose signs/sx & management

A
  • Sx: Hematuria, gum bleed, excessive menstrual bleeding
  • INR < 4.5: reduce or skip dose
  • INR 4.5-10: hold 1-2 doses
  • INR > 10 w/out bleed: hold, administer vit K
  • Major bleed: hold, slow vit K infusion + Prothrombin complex concentrate (better than fresh frozen plasmin) or recombinant factor VIIa
40
Q

Dabigatran: MOA

A

• Acts in plasma to directly inhibit the activity of thrombin (IIa)

41
Q

Dabigatran : Pharmacokinetics

A
  • Oral = rapidly absorbed as prodrug
  • Renal excretion
  • Requires frequent monitoring and dosage adjustments
42
Q

Dabigatran :Uses

A

• Reduce risk of systemic embolism w/non-valvular afib (not VTE)

43
Q

Dabigatran : Adverse Rxns

A
  • Bleeding
  • GI complaints
  • Fewer drug interactions
44
Q

Warfarin vs. Dabigatram in aFib

A
  • Warfarin=long history of use, once-daily dosing, reversal w/vitK, but requires INR monitoring, drug interactions
  • Dabigatran=lower rates of strokes/intracranial complications, no INR monitoring or diet restrictions, fewer drug rxns, but no good monitoring tool, no specific antidote, twice-daily dowing, storage challenges, and renal adjustment
45
Q

Rivaroxavan/Apixaban: MOA

A

• Acts in the plasma to directly inhibit the activity of factor Xa

46
Q

Rivaroxavan/Apixaban : Pharmacokinetics

A
  • Oral

* Hepatic metabolism and renal excetrion

47
Q

Rivaroxavan/Apixaban :Uses

A
  • Reduce risk of systemic embolism in patients w/non-valvular aFib
  • Approved for prevention and tx of DVT/VTE
48
Q

Rivaroxavan/Apixaban : Adverse Rxns

A
  • Bleeding

* No antidote for rapid reversal

49
Q

Warfarin vs. Rivaroxavan/Apixaban in aFib

A
  • Adv of Riv/Apix: lower rates of stroke/bleeding, no INR, no dietary restrictions, once-daily dosing (Riv)
  • Disadv: no monitoring tool, no specific antidote, bid dosing (Apix), renal dosing
50
Q

Main antiplatelet agents

A
  • Aspirin
  • Clopidogrel
  • Dipyridamole
  • Abciximab, Eptifibatide, Tirofibanm
51
Q

Aspirin: MOA

A

• Inhibition of COX-1 synthesis of thombroxane (COX-1 inhibit > COX-2 @ endothelial cells)

52
Q

Aspirin : Pharmacokinetics

A
  • Oral

* Low-dose daily dosing

53
Q

Aspirin :Uses

A
  • Acute MI (STEMI) (w/ADP antagonist)
  • Unstable angina/NSTEMI
  • Percutaneous coronary interventions (w/ADP antagonist)
  • Secondary prevention of MI/ischemic stroke
54
Q

Aspirin : Adverse Rxns

A
  • Rare w/low-dose therapy

* GI complaints or bleeding

55
Q

Clopidogrel (Plavix): MOA

A
  • ADP receptor antagonists → interferes w/ADP-induced platelet aggregation via irreversible inhibition
  • Synergistic actions w/aspirin
56
Q

Clopidogrel (Plavix): Pharmacokinetics

A

• Once-daily dosing w/loading dose

57
Q

Clopidogrel (Plavix):Uses

A
  • Acute MI (STEMI) (w/aspirin)
  • Sometimes: Unstable angina/NSTEMI
  • Percutaneous coronary interventions (w/asprin)
58
Q

Clopidogrel (Plavix)/Other ADP antagonists: Adverse Rxns

A
  • Clopidogrel: GI upset, headache, dizziness, URI, bleeding
  • Prasugrel: bleeding
  • Tricagrelor: bleeding
59
Q

Dipyridamole: MOA

A

• Blocks phosphodiesterase breakdown of cAMP → prostacyclin anti-aggregatory effect

60
Q

Dipyridamole : Pharmacokinetics

A
  • Oral

* 3-4x before meals

61
Q

Dipyridamole :Uses

A

• ischemic stroke: dipyridamole + aspirin

62
Q

Dipyridamole : Adverse Rxns

A

• minimal and transient

63
Q

Abciximab: MOA

A

• blocks IIb/IIIa receptors on platelet → prevents integrin and fibrinogen binding

64
Q

Abciximab : Pharmacokinetics

A

• continuous IV infusion

65
Q

Abciximab :Uses

A

• Percutaneous coronary interventions (PCI): aspirin + ADP antagonists + GIIb/IIa inhibitors

66
Q

Abciximab : Adverse Rxns

A

• Bleeding

67
Q

Thrombolytics: MOA

A
  • Increased formation of plasmin from plasminogen
  • Streptokinase = activates free and fibrin-bound plasminogen
  • tPA = activates bound plasminogen
68
Q

Streptokinase characteristics

A

• systemic activation of plasmin

69
Q

Tissue Plasminogen Activator (tPA) characteristics

A

• recombinant tPA → binds to fibrin and activates bound plasminogen

70
Q

Reteplase/Tenecteplase characteristics

A
  • given bolus w/prolonged duration of action

* less fibrin-specific than tPA

71
Q

Thrombolytics: Uses

A
  • Acute MI → coronary artery thrombosis
  • DVT
  • Multiple PE
72
Q

Thrombolytics: Adverse Effects

A

• hemorrhage

CVPR: CV Unit II (17 decks)

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