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Flashcards in Antithrombotic and hemostatic drugs Deck (35):
1

Define/ describe the three main classes of antithrombotic drugs

- anticoagulants: used to treat or prevent venous thrombosis
- antiplatelets: used to prevent arterial thrombosis
- thromboyltic agents: used to acutely reverse thrombosis

2

What is the mechanism of the anticoagulant effect of heparin?

accelerates inhibition of coagulation proteases Xa and IIa (thrombin) by antithrombin

heparin binds to antithrombin and induces a conformational change that accelerates the rate of protease inhibition

3

What property in addition to anticoagulation is notable in heparin?

anti-inflammatory

4

Describe the pharmacology of unfractionated heparin

- unpredictable kinetics, monitor with aPTT
- can inhibit Xa and IIa
- side effects: bleeding, HIT, osteoporosis
- neutralized by protamin

5

Describe the pharmacology of low molecular weight heparin

- effects on Xa> IIa (thrombin)
-does not reliably prolong aPTT
- cleared mainly by kidneys
- only partially neutralized by protamine
- no need for routine monitoring and fewer complications

6

Describe the pharmacology of fondaparinux

- specifically inhibits Xa
- longer half life
- does not require monitoring
- eliminated by kidneys
- can be used in HIT
- not neutralized by protamine

7

List indications for use of heparins

- LMWH is DOC for DVT/PE, can transition to warfarin
- prevention of post-op thrombosis and during acute MI
- UFH in dialysis and cardiopulmonary bypass machines
_LMWH is DOC in pregnancy

8

Describe the mechanism of action of warfarin

Warfarin acts by interfering with the vitamin K-dependent gamma carboxylation of glutamines within
the amino-terminus “Gla domain” of the coagulation proteases

Interferes with reduction of vitamin K and depletes the body of this vitamin

9

Warfarin is monitored using the

PT/INR, goal is 2.0-3.0

10

List indications for warfarin

- prevent recurrence of VTE, give for 3-6 months after an event
- reduce risk of stroke and arterial emboli in atrial fibrillation or artificial valves

11

What can be given to reverse a warfarin overdose?

Vitamin K

12

Warfarin should never be given to __________

pregnant women
can cross placenta

13

_________ is a complication of warfarin thought to be due to suppression of protein C

warfarin induced skin necrosis

14

List some drugs that potentiate the effects of warfarin

- inhibitors of warfarin metabolism: phenytoin, metronidazole, chloramphenicol, cimetidine, disulfiram, acute EtOH

- displacement of warfarin from albumin: aspirin, clofibrate

- inhibition of platelet aggregation: aspirin, clobidogrel

- decreased vitamin K synthesis: antibiotics

15

List drugs that decrease warfarin effects

- drugs that stimulate warfarin metabolism: barbiturates, rifampin, chronic EtOH

16

List and describe three direct thrombin inhibitors

- argatroban: monitor by aPTT
- bivalirudin: IV drug cleared by kidneys, used in percutaneous coronary angioplasty and HIT
- dabigatran: oral alternative to warfarin, no routine monitoring and no antidote

17

List a drug that is a direct factor Xa inhibitor

rivaroxaban: used to prevent VTE in orthopedic surgeries, stroke prevention in atrial fibrillation, tx of VTE

18

Describe the mechanism of action of aspirin

inhibits platelet activation by irreversibly inhibiting COX-1 which prevents conversion of arachidonic acid to TXA2

19

How do other NSAIDs that reversibly inhibit COX interact with aspirin?

compete with aspirin for binding to COX1, they can interfere with the anti-platelet effects
of aspirin

20

List indications for aspirin use

unstable angina
prevention of thrombosis after CABG
Coronary angioplasty
prevention of thrombosis in artificial heart valves
prevention of acute MI
TIA prophylaxis

21

List side effects of aspririn

GI or cerebral bleed, rash, tinnitis

22

What is the mechanism of action of clopidogrel

inhibits ADP-dependent platelet aggregation by binding to the ADP receptor

23

20-30% of people have a CYP2C polymorphism that results in lower production of the active metabolite of _____, resulting in non-response

clopidogrel

24

List indications of clopidogrel

TIA- may be superior to aspirin
Acute coronary syndrome
Prevention of coronary stent occlusion

25

List major side effects of clopidogrel

immune mediated thrombocytopenia, neutropenia
hemorrhage
drug interactions

26

List two drug names that are LMWH

enoxaparin, dalteparin

27

What is the mechanism of action of abciximab?

inhibits platelet aggregation by inhibiting binding of fibrinogen and vWF.
monoclonal antibody against GpIIb/IIIa

28

List indications for abciximab

adjunct therapy to percutaneous coronary intervention
useful in unstable angina if not responding to conventional therapy

29

What is the mechanism of action of eptifibatide and tirofiban?

Mimic a peptide that is a ligand for GpIIb/IIIa, thus inhibiting fibrinogen binding and preventing aggregation of platelets

30

What is the mechanism of action of reteplase and alteplase?

tPA recombinant forms, work by converting plasminogen to plasmin so it can digest the fibrin thrombus

31

List some indications for fibrinolysis (reteplase and alteplase)

acute MI
acute peripheral arterial obstruction
ischemic stroke
massive PE with hemodynamic compromise
massive proximal DVT

32

List factors that determine the success of thrombolytic therapy

time to administration
character of the thrombus
re-occlusion

33

List three indications for DDAVP

A hemostatic drug used in type I vWF, mild hemophilia, and thrombocytopenia

34

List indications for amicar

Hemostatic drug that inhibits plasminogen activation
used for post-op bleeding, to reduce bleeding in coronary bypass, to reverse bleeding due to thrombolytic drugs

35

What are indications for recombinant factor VIIa?

hemophilia if inhibitors have developed against replacement coagulation factors

uncontrolled hemorrhage