Chapter 34: Anticoagulation Flashcards
(123 cards)
1
Q
What are anticoagulants used for?
A
To prevent blood clot formation but do not break down the existing clot
2
Q
What does VTE stand for?
A
Venous Thromboembolism
3
Q
What conditions are anticoagulants used to prevent and treat?
A
VTE, which refers to DVT and PE
4
Q
In what situation are anticoagulants used for immediate treatment?
A
Acute coronary syndrome and the prevention of cardioembolic stroke
5
Q
What factors does Warfarin inhibit the activation of?
A
Factors II, VII, IX, X
6
Q
What are DOACs preferred for?
A
Stroke prevention in AF
7
Q
When should warfarin be used instead of DOACs in AF?
A
If there is moderate-to-severe mitral stenosis or a mechanical heart valve
8
Q
What is the recommended treatment for VTE?
A
Use DOACs
9
Q
When should warfarin be used for VTE treatment?
A
If the patient has antiphospholipid syndrome or a mechanical heart valve
10
Q
What type of drug is warfarin?
A
Vitamin K antagonist
11
Q
What is a key characteristic of warfarin?
A
Narrow therapeutic range requiring careful monitoring of INR
12
Q
What does Antithrombin (AT) do?
A
Inactivates thrombin (factor IIa) and Xa involved in blood clotting
13
Q
How do unfractionated heparin (UFH), low molecular weight heparins (LMWHs), and fondaparinux work?
A
By binding to Antithrombin (AT)
14
Q
Which type of heparin inhibits factor Xa more specifically?
A
Low molecular weight heparins (LMWHs)
15
Q
What is the mechanism of action of fondaparinux (Arixtra)?
A
Selective inhibition of factor Xa
16
Q
What do apixaban (Eliquis), edoxaban (Savaysa), and rivaroxaban (Xarelto) do?
A
Inhibit factor Xa directly
17
Q
What do UF and LMWH inhibit indirectly?
A
Thrombin and factor Xa through AT binding
18
Q
What is the mechanism of action of Direct Thrombin Inhibitors (DTTs)?
A
Block thrombin directly, decreasing the amount of fibrin available for clot formation
19
Q
What are intravenous Direct Thrombin Inhibitor?
A
- Argatroban
- Bivalirudin
20
Q
Why are intravenous DTIs important clinically?
A
They do not cross-react with heparin-induced thrombocytopenia (HIT) antibodies
21
Q
What is the oral Direct Thrombin Inhibitor?
A
Dabigatran (Pradaxa)
22
Q
What does unfractionated heparin (UFH) bind to?
A
Antithrombin (AT)
23
Q
What is the primary use of unfractionated heparin?
A
Prevention of VTE and treatment of VTE and ACS/STEMI
24
Q
What is the dosing for prophylaxis of VTE with unfractionated heparin?
A
5,000 units SC Q8-12H
25
What is the dosing for treatment of VTE with unfractionated heparin?
80 units/kg IV bolus; 18 units/kg/hr infusion
26
What is the dosing for treatment of ACS/STEMI with unfractionated heparin?
60 units/kg IV bolus; 12 units/kg/hr infusion
27
What are the contraindications for using unfractionated heparin?
* Uncontrolled active bleed
* Severe thrombocytopenia
* History of HIT
28
What is a warning associated with unfractionated heparin?
Fatal medication errors: verify the correct concentration is chosen
29
What are some side effects of unfractionated heparin?
* Bleeding
* Thrombocytopenia
* Hyperkalemia
30
What monitoring is required for unfractionated heparin?
* aPTT or anti-Xa level
* Platelets, Hgb, Hct at baseline and daily
31
When to check aPTT?
6 hours after initiation and q6h until therapeutic
32
What is the therapeutic range for aPTT when using unfractionated heparin?
1.5-2.5x control
33
What is the antidote for unfractionated heparin?
Protamine
34
What are Heparin lock-flushes used for?
Keep IV lines open
35
What can suggest possible HIT when monitoring platelets?
A decrease in platelets > 50% from baseline
36
What is the trade name of Enoxaparin?
Lovenox
37
What is the dosing for prophylaxis of VTE with Enoxaparin?
30 mg SC Q12H or 40 mg SC daily
38
What is the dosing for treatment of VTE/UA/NSTEMI with Enoxaparin?
* 1 mg/Kg SC Q12H
or
* 1.5 mg/Kg SC daily
39
What is the treatment dose for VTE in patients with a CrCl < 30 mL/min using Enoxaparin?
1 mg/kg SC daily
40
What is the initial treatment dose of Enoxaparin for STEMI in patients < 75 years?
30 mg IV bolus plus 1 mg/kg SC dose followed by 1 mg/kg SC Q12H
41
What are the contraindications for LMWHs?
* History of HIT
* Active major bleed
* Hypersensitivity to pork
42
What are common side effects of LMWHs?
* Bleeding
* Anemia
* Injection site reactions
* Thrombocytopenia (including HIT)
43
What monitoring parameters are recommended for patients on LMWHs?
* Platelets
* Hemoglobin (Hgb)
* Hematocrit (Hct)
* Serum creatinine (SCr)
44
What is the antidote for LMWHs?
Protamine
45
What should not be done prior to injecting LMWH from a syringe?
Expel the air bubble
46
What storage condition is recommended for LMWHs?
Room temperature
47
What is heparin-induced thrombocytopenia (HIT)?
An immune-mediated IgG drug reaction that causes platelet activation and a release of pro-coagulant microparticles which leads to the prothrombotic state
48
What type of immune response is involved in HIT?
IgG drug reaction
49
What does HIT lead to in the body?
Prothrombotic state
50
How to diagnose HIT?
4Ts score:
1. Thrombocytopenia: an unexplained > 50% drop in platelet count from baseline is highly suspicious of HIT.
2. Timing of platelet count drop: the typical onset of HIT occurs 5 - 10 days after the start of heparin
3. Thrombosis
4. Other causes
51
List confirmatory Lab tests for HIT
1. ELISA
2. SRA
3. Heparin-induced platelet aggregation
52
HIT management
1. stop all forms of heparin and LMWH
2. If on warfarin: the warfarin should be discontinued and vitamin K should be administered.
3. For the immediate treatment of HIT, rapid-acting non-heparin anticoagulants (e.g., argatroban) are to be used.
4. Do not start warfarin therapy until the platelets have recovered to ≥ 150,000 cells/mm'.
5. If urgent cardiac surgery or PCI is required, bivalirudin is the preferred anticoagulant.
53
What is fondaparinux and how does it inhibit factor Xa?
Fondaparinux (Arixtra) is an injectable synthetic pentasaccharide that selectively inhibits factor Xa via binding to antithrombin (AT), making it an indirect inhibitor of factor Xa.
54
What is the dosing for Apixaban in nonvalvular AF for stroke prophylaxis?
5 mg PO BID
55
What is the initial dosing for Apixaban in the treatment of DVT/PE?
10 mg PO BID x 7 days, then 5 mg PO BID.
56
What are the boxed warnings for all direct factor Xa inhibitors?
Patients receiving neuraxial anesthesia (epidural, spinal) or undergoing spinal puncture are at risk of hematomas and subsequent paralysis.
57
What is the contraindication for factor Xa inhibitors?
Active pathological bleeding.
58
What is the recommended dosing for Rivaroxaban in nonvalvular AF with CrCl > 50 mL/min?
20 mg PO daily with evening meal.
59
What is the dosing for Rivaroxaban in the treatment of DVT/PE?
Initial: 15 mg PO BID x 21 days, then 20 mg PO daily with food.
60
What should be done if a dose of Rivaroxaban is missed?
Administer the dose as soon as possible on the same day.
61
What is the recommendation for Edoxaban in nonvalvular AF with CrCl >95 mL/min?
avoid use
62
What is the antidote for apixaban and rivaroxaban?
andexanet alfa (Andexxa).
63
Which oral factor Xa inhibitor requires bridging for DVT treatment and for how long?
Edoxaban for 5-10 days
64
What is the dosing for Rivaroxaban in patients with CrCl < 15 mL/min?
avoid
65
From warfarin to another oral anticoagulant, stop warfarin and convert to:
* Rivaroxaban when INR is < 3
* Edoxaban when INR is ≤ 2.5
* Apixaban when INR is < 2
* Dabigatran when INR is < 2
66
What do direct thrombin inhibitors do?
Directly inhibit thrombin (factor IIa) by binding to the active site of free and clot-associated thrombin.
67
What is the brand name of the oral direct thrombin inhibitor?
Dabigatran (Pradaxa)
68
What should be done if a dose of Dabigatran is missed?
Take immediately unless it is within 6 hours of the next scheduled dose; do not double the dose.
69
What is the dosing for Dabigatran for the treatment of DVT/PE?
150 mg BID, starting after 5-10 days of parenteral anticoagulation.
70
What is Bivalirudin indicated for?
Patients undergoing PCI, including those with HIT.
71
What are some drug interactions with Dabigatran?
* Avoid concurrent use with rifampin
* Reduce dose to 75 mg BID if CrCl is 30-50 mL/min with dronedarone or systemic ketoconazole.
72
What are the boxed warnings for Dabigatran?
* Risk of hematomas and paralysis with neuraxial anesthesia
* Risk of thrombotic events with premature discontinuation.
73
What are the contraindications for using Dabigatran?
Active pathological bleeding, treatment of patients with mechanical prosthetic heart valves.
74
What are common side effects of Dabigatran?
* Dyspepsia
* Gastritis-like symptoms
* Bleeding (including GI bleeding).
75
What is the antidote for Dabigatran?
Idarucizumab (Praxbind).
76
What precautions should be taken when dispensing Dabigatran?
Dispense in original container; discard 4 months after opening.
77
How should Dabigatran capsules be taken?
Swallow whole; do not break, chew, crush, or open; do not administer by NG tube.
78
What should be noted about Argatroban and HIT?
Safe with active HIT or history of HIT; no cross-reaction with HIT antibodies.
79
What is the mechanism of action of warfarin?
Warfarin competitively inhibits the C1 subunit of the multi-unit vitamin K epoxide reductase (VKORC1) enzyme complex
80
What is the recommended initial dosing for healthy outpatients taking warfarin?
≤ 10 mg daily for the first 2 days, then adjust dose per INR
## Footnote
Lower doses (≤ 5 mg) are recommended for elderly, malnourished patients, or those on drugs that can affect warfarin levels.
81
What should be done if a dose of warfarin is missed?
Take the missed dose immediately on the same day; do not double the dose the next day
82
List some contraindications for warfarin use.
* Pregnancy (except with mechanical heart valves at high risk for thromboembolism)
83
What are some warnings associated with warfarin?
* Tissue necrosis/gangrene
* HIT (contraindicated as monotherapy in the initial treatment of active HIT)
* Systemic atheroemboli and cholesterol microemboli (purple toe syndrome)
* Presence of CYP2C9*2 or *3 alleles and/or polymorphism of VKORC1 gene may increase bleeding risk
84
What are common side effects of warfarin?
* Bleeding/bruising (mild to severe)
* Skin necrosis
85
What is the target INR for most indications while on warfarin?
Goal INR 2-3 (target 2.5)
86
What is the higher target INR for high-risk indications?
Goal INR 2.5-3.5 (target 3)
## Footnote
This includes mechanical mitral valve, 2 mechanical heart valves, or mechanical aortic valve with 1 additional risk factor.
87
When should INR monitoring begin for patients on warfarin?
After the initial 2 or 3 doses or if on a chronic, stable dose, monitor every 4-12 weeks
## Footnote
Monitoring should also include Hct, Hgb, and signs of bleeding.
88
What is the antidote for warfarin?
Vitamin K
89
Name drugs that is a CYP2C9 inhibitor and can increase INR.
1. Amiodarone
2. Fluconazole
3. Metronidazole
4. Bactrim
90
What are some CYP2C9 inducers that can decrease INR?
* Carbamazepine
* Phenobarbital
* Phenytoin
* Rifampin
* St. John's wort
91
What are the most common pharmacodynamic drug interactions with warfarin that increase bleeding risk?
NSAIDs, antiplatelet agents, other anticoagulants, SSRIs, SNRIs
92
List the colors and dosages of warfarin tablets.
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* Pink (1 mg)
* Lavender (2 mg)
* Green (2.5 mg)
* Brown/Tan (3 mg)
* Blue (4 mg)
* Peach (5 mg)
* Teal (6 mg)
* Yellow (7.5 mg)
* White (10 mg)
93
Name some natural products that increase bleeding risk when used with warfarin.
* Chondroitin
* Dong quai
* High doses of fish oils
* The '5 Gs' (garlic, ginger, ginkgo, ginseng, glucosamine)
* Vitamin E
* Willow bark
94
Which natural products can decrease the effectiveness of warfarin?
* St. John's wort
95
Fill in the blank: Foods high in _______ can affect INR levels.
Vitamin K
96
List foods that are high in vitamin K.
* Spinach (cooked)
* Broccoli
* Brussels sprouts
* Collard greens
* Kale
97
When should warfarin be started in patients with acute DVT/PE?
While the patient is still receiving a parenteral anticoagulant
98
What criteria must be met to discontinue parenteral anticoagulants when on warfarin?
INR must be ≥ 2 for at least 24 hours, measured on two consecutive days
99
What should be done for patients with stable therapeutic INRs who present with a single low INR value?
Continue current dose and obtain another INR within 1 - 2 weeks
100
How often can INR testing be done for patients with consistently stable INRs on warfarin therapy?
Up to every 12 weeks
## Footnote
This is less frequent than the usual 4-week testing.
101
Vitamin K brand name
Mephyton
102
Mephyton route of administration
PO/IV
103
Which clotting factors are in Kcentra?
* II
* VII
* IX
* X
* Protein C & S
104
Kcentra should be administered with_____
Vit K
105
What is the protamine dose for IV UFH reversal?
1 mg protamine will reverse 100 units of heparin.
Reverse the amount of heparin given in the last 2-2.5hr max dose 50mg
106
What is the protamine dose for IV LMWH reversal?
1 mg protamine per 1mg enoxaparin
107
What are the symptoms of a DVT?
Pain in the affected limb and unilateral lower extremity swelling
108
What are the symptoms of a PE?
Shortness of breath and chest pain
109
How can DVTs be diagnosed?
Ultrasound
110
What are the modifiable risk factors for VTE?
* Acute medical illness
* Immobility
* Medications (e.g., SERMs, drugs containing estrogen, erythropoiesis-stimulating agents)
* Obesity (BMI ≥ 30 kg/m2)
* Pregnancy and postpartum period
* Recent surgery or major trauma
111
What are the non-modifiable risk factors for VTE?
* Increasing age
* Cancer or chemotherapy
* Previous VTE
* Inherited or acquired thrombophilia (e.g., antithrombin deficiency, factor V Leiden, antiphospholipid syndrome, protein C or S deficiency)
* Certain disease states (e.g., heart failure, nephrotic syndrome, respiratory failure)
112
What is the recommended treatment duration for VTE caused by surgery or a reversible risk factor?
Three months
113
When should the duration of therapy for VTE be extended?
If the VTE is unprovoked and the patient's bleeding risk is low-to-moderate
114
What anticoagulants are approved for VTE prophylaxis?
* UFH
* LMWHs
* Fondaparinux
* Rivaroxaban
* Apixaban
* Dabigatran
115
What are the non-drug alternatives for VTE prevention?
* Intermittent pneumatic compression (IPC) devices
* Graduated compression stockings
116
What recommendations should long-distance travelers at risk for VTE follow?
* Frequent ambulation
* Calf muscle exercises
* Sitting in an aisle seat
* Using graduated compression stockings with 15 - 30 mmHg of pressure at the ankle
117
What should not be used for VTE prevention in travelers?
Aspirin or anticoagulants
118
What is the preferred treatment for patients without cancer for the first three months of DVT or PE treatment?
Dabigatran and the oral factor Xa inhibitors (rivaroxaban, apixaban, and edoxaban)
119
What is the recommendation for patients with cancer regarding oral anticoagulants?
Oral factor Xa inhibitors are preferred over other oral anticoagulants and LMWH
120
What should be recommended for patients with an unprovoked DVT or PE who are stopping anticoagulation?
Aspirin to prevent recurrence (if no contraindications)
121
What medications are contraindicated in patients with a history of VTE?
Estrogen-containing medications and selective estrogen receptor modulators (SERMs)
122
What is preferred for the prevention and treatment of VTE in pregnant women?
LMWH
123
Who requires stroke prevention anticoagulation with afib?
CHA2DS2-VASc >= 2 for male and >= 3 for female
