Anticoagulation Flashcards
(51 cards)
1
Q
Steps of Normal Hemostasis
A
- injury
- vasospasm decreases blood flow, platelet aggregation
- platelets form plug
- coagulation activation = fibrin clot
- clot removed by fibrinolysis
2
Q
Virchow’s Triad
A
- hypercoagulability
- vascular injury
- venous stasis (blood pooling)
3
Q
What activates the clotting cascade? What inhibits the cascade?
A
- clotting factors activate
- anticoagulants inhibit
4
Q
Unfractionated Heparin MOA
A
- inactivates thrombin and other clotting factors
- prevents conversion of fibrinogen to fibrin
- prevents coagulation
5
Q
Indications for UFH
A
- venous thromboembolism tx and Px
- unstable angina
- acute MI
- coronary bypass surgery
- hemodialysis
- angioplasty
- IV line flushes
6
Q
How does the half life of UFH change at different doses?
A
-half life increases with increasing doses
7
Q
UFH AEs
A
- hemorrhage
- heparin induced and heparin associated thrombocytopenia
- osteoporosis and hyperkalemia w/ long term use
8
Q
Heparin Induced Thrombocytopenia
A
- platelets < 100,000 or <50% baseline
- need to discontinue heparin if this occurs
- initiate alternative anticoagulation
- more worrisome than heparin associated thrombocytopenia
9
Q
Heparin Associated Thrombocytopenia
A
- mild thrombocytopenia
- platelets rarely drop <100,000
- manage w/ observation
10
Q
UFH Pregnancy Use
A
-category C, can be used
11
Q
Dosing of UFH
A
- loading dose followed by continuous infusion
- can be given subQ for non-acute situations
12
Q
Monitoring of UFH
A
- check aPTT at 6 hours and adjust dose as needed
- aPTT should be higher than the reference range
13
Q
What should be given to reverse heparin?
A
protamine
14
Q
LMWH MOA
A
-inhibit clotting factor Xa
15
Q
How does the half life of LMWH compare to UFH?
A
-LMWH half life is longer so q12 hour dosing
16
Q
What are the generic and trade names for LMWH?
A
- generic: enoxaparin
- trade: Lovenox
17
Q
LMWH AEs
A
- hemorrhage
- thrombocytopenia: lower incidence of HIT than with heparin, check platelets on day 3
- injection site hematoma, minor bleeding
- osteoporosis
18
Q
LMWH Monitoring
A
- routine monitoring not necessary
- antifactor Xa activity may be helpful in pts with low CrCl, morbid obesity, during pregnancy or therapy longer than 14 days
19
Q
What should be given to reverse LMWH?
A
- protamine
- but it dose not neutralize anticoagulation of LMWH completely
20
Q
Fondaparinux/Arixtra MOA
A
- inhibits factor Xa
- inhibits thrombin formation and thrombus development
21
Q
What has limited the use of direct thrombin inhibitors?
A
-relatively high incidence of bleeding in clinical trials and high cost
22
Q
Warfarin MOA
A
-vitamin K antagonist –> blocks production of vitamin K dependent clotting factors
23
Q
Warfarin Indications
A
- venous thromboembolism tx and Px
- acute MI
- prosthetic heart valves
- atrial fib
- TIA/stroke
- hypercoagulable states
- peripheral arterial occlusive dz
24
Q
Warfarin Absorption
A
-97-99% GI tract
25
Warfarin AEs
- hemorrhage
- skin necrosis (rare, appears early)
- purple toe syndrome (3-10 weeks after therapy start
26
Warfarin CIs
- pregnancy cat X
- pts with additional risks for hemorrhage
- noncompliance w/ drug therapy or monitoring
- alcoholism
- surgery, dental work
- spinal anesthesia or spinal injections
27
Warfarin Dosing
- qday, usually overlapped with heparin 4-5 days
| - dosing very patient specific and available in many strengths
28
Warfarin Monitoring
- INR: international normalized ratio; established to standardize monitoring
- INR reference range about 1
- most goal ranges are 2.0-3.0 (up to 3.5 for prosthetic heart valve pts)
29
What should be given to reverse warfarin?
vitamin K or fresh frozen plasma
30
Warfarin Drug Interactions
- many; assume interaction until proven otherwise
| - key ones: SMX, NSAIDs, aspirin
31
Warfarin Food Interactions
-foods with high amounts of vitamin K will antagonize warfarin (eg green veggies, MVI with vit K, other dietary supplements)
32
Effects of Alcohol on Warfarin:
1. Acute EtOH Ingestion
2. Chronic EtOH Ingestion
3. Cirrhosis
1. acute increases INR
2. chronic decreases INR
3. cirrhosis increases INR
33
Dabigatran/Pradaxa MOA
-direct thrombin inhibitor
34
Dabigatran/Pradaxa Indications
-thromboembolism (stroke) prevention in afib
35
Dabigatran/Pradaxa AE
-bleeding, GI complaints
36
Dabigatran/Pradaxa CI
- active, pathologic bleeding
| - previous hypersensitivity reaction
37
What is the advantage of Dabigatran/Pradaxa over warfarin? Disadvantages?
- prevents 5 more strokes/1000 pts/yr
- causes more GI bleeding than warfarin
- $250/mo compared to 80/mo for warfarin
- no antidote
38
Rivaroxaban/Xarelto MOA
-oral factor Xa inhibitor
39
Rivaroxaban/Xarelto Indications
- thromboembolism (stroke) prevention in afib
| - prevent thrombosis after knee or hip surgery
40
Rivaroxaban/Xarelto AE
-bleeding
41
Rivaroxaban/Xarelto CI
- active major bleeding
| - hypersensitivity
42
Rivaroxaban/Xarelto AE and Costs Compared to Warfarin
- greater risk of GI bleeding than warfarin
- $230/mo compared to 80/mo for warfarin
- no antidote
43
Apixaban/Eliquis MOA
-oral factor Xa inhibitor
44
Apixaban/Eliquis Indications
- thromboembolism (stroke) prevention in afib
| - prevent thrombosis after knee or hip surgery
45
Apixaban/Eliquis AE
-bleeding
46
Apixaban/Eliquis CI
- active pathologic bleeding
| - hypersensitivity
47
What are the advantages of Apixaban/Eliquis over warfarin? Disadvantages?
- for every 1000 pts/yr, prevents more strokes, avoids more major bleeds and prevents more deaths than warfarin
- more expensive than warfarin
- no antidote
48
What are the options for prevention of VTE?
- heparin
- LMWH
- Fondaparinux
- graduated compression stockings
49
What are the options for treatment of VTE?
- parenteral anticoagulant and warfarin
| - thrombolytics (generally not used)
50
VTE Parenteral Anticoagulant and Warfarin Treatment
- parenteral anticoag for 5-7 days: continuous infusion heparin, subQ UFH, LMWH, Fondaparinux
- warfarin therapy begins on day 1 after first dose of parenteral anticoag
- overlap parenteral and oral anticoag therapy x5 days
- must have therapeutic INR 2 days in a row before stopping heparin
51
CHADS2 Score
- CHF
- HTN
- Age > 75 years
- DM
- Stroke or TIA history (x2 points)
