Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

IPFC 3 Midterm 2 > VTE Chronic Therapy > Flashcards

VTE Chronic Therapy Flashcards

1
Q

What is the half-life of warfarin
How long until 95% steady state

A

t-1/2: 48 hours
95% SS: 10 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

What day was INR found to be predictive of maintenance dose in A. fib

A

Day 3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why can it take up to 3 weeks to reach steady state INR values

A

Factor II lasts the longest
Half-life of disappearance of factor II: up to 72 hours
95% SS = 15 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How often should INR be checked for outpatients

A

twice weekly for the first month

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the equation for maintenance dose if the 10mg initiation was used?

A

2.5 mg + 10% week 1 dose - INR day 8 + 1.5mg (if INR at D5 was less than 2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the longest time INR tests should be monitored

A

4-6 weeks

however 12 weeks was non-inferior to 4 weeks in one study

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How long can transition state last up to to reach maintenance phase

A

3 months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are warfarin dose adjustment alternatives (3) Which one’s don’t work?

A
  1. Just respond to the INR (NEVER DO THIS)
  2. Use a validated dosing adjustment instrument
    - computerized warfarin managements systems
    - Hard copy algorithm (ex. mcmaster 2-step nomogram)
  3. Use a systematic approach to patient evaluation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the systematic approach to warfarin dose adjustments (4)

A
  1. Try to figure out why
  2. Determine patient’s risk of thrombosis
  3. Consider how far INR is out of range
  4. Consider alternatives
    (a. no changes, repeat INR sooner)
    (b. one-time adjustment dose, then resume maintenance dose)
    (c. change maintenance dose)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are reasons that INR is fluctuating? (7)

A
  1. Non-adherence
  2. Changes in meds (addition/deletion)
  3. Acute illnesses (GI, diarrhea)
  4. Dietary habit changes
  5. Lifestyle habits (alcohol, exercise, travel)
  6. Stress
  7. Inaccurate INR test
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the % chance of getting a clot again with no therapy after:
1 month
1-3 months
Recurrent VTE

A

1 month: 40% per month (>1% per day)
1-3 months: 10% per 2 months (>0.15% per day)

Recurrent VTE: 15% per year (0.04% per day)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How far can the INR be out of range? What do you do?
When do you adjust if not in range? (2)

A

If less than 0.5 units difference
- repeat INR in 1-2 weeks

Adjust if:
- over 0.5+ units difference
OR
- within the first 1-3 months
(assuming they missed a dose, just give back their dose)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How do you adjust if multiple INR tests are
+/- 0.5 units
over 0.5 units

A

+/- 0.5 units
- 5-10% of weekly dose

over 0.5 units
- 10-20% of weekly dose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Changes in INR seen within a day or 2 reflect changes in what factor?

A

Factor VII 7 concentrations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the mechanisms for warfarin drug interactions (5)

A
  1. Inhibition of platelet function
    - these drugs inhibit primary hemo, warfarin inhibits secondary hemo –> addidtive effect –> BLEED RISK
    - ASA, clopidogrel, NSAIDs
  2. Reduced synthesis of vitamin K by gastrointestinal flora
    some antibiotics
  3. Alteration of warfarin metabolism
    - especially inhibitors/inducers of CYP 2C9 (eg. cotrimaxazole, flucanozole, amiodorone)
  4. Injury to GI mucosa
    - NSAIDs have risk of stomach ulcer, passage for bleeding
  5. Interference with vitamin K epoxide-reductase
    - Acetaminophen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

When is the mechanism of reduced synthesis of vitamin K by GI flora only an issue? (3)

A
  • Antibiotic is inhibitor of CYP450 enzymes
  • Patient is very ill with fever/reduced apetite or activity
  • Antibiotic caused diarrhea as a side effect
16
Q

Which of the 5 mechanisms would affect INR values (3)

A
  • Reduced synthesis of vitamin K by GI (antibiotics)
  • Alteration of warfarin metabolism (CYP 2C9 inhibitors/inducers, -azoles)
  • Interference with vitamin K reductase (acetaminophen)
17
Q

Recommendation for the following on warfarin:
interaction? INR? Monitor time?
Starting therapy today with acetaminophen 1g q6h

A
  • Interacts w/ warfarin, inc INR
  • 1-1.3g of tylenol requires INR testing
  • Come back in 3 days to adjust warfarin dose
18
Q

Recommendation for the following on warfarin:
interaction? INR? Monitor time?
Starting therapy with bisoprolol 5mg once daily

A
  • No interaction
  • Any new drug come back in 1 week for INR test
19
Q

Recommendation for the following on warfarin:
interaction? INR? Monitor time?
Starting therapy with naproxen 200mg once daily

A
  • Interaction, inc risk of bleeding
  • No INR change
  • try using topical NSAIDs, or cox-2 selective, or PPI
  • can switch to tylenol if need be
  • monitor INR
20
Q

Recommendation for the following on warfarin:
interaction? INR? Monitor time?
planning to stop taking glucosamine after 4 months since it was not working

A
  • unknown interaction
  • follow up INR in 1 week
21
Q

How much % does ASA increase bleed risk in patients taking warfarin?

A

50%

22
Q

Which group of patients may require ASA in addition to warfarin (3)

A
  1. Recent acute coronary syndrome (MI)
  2. Recent coronary stent/coronary bypass procedure
  3. Mechanical heart valves
23
Q

What is the risk for the following INR values
over 4
over 5
over 6

A

over 4
- risk of major bleeding

over 5
- risk of intracranial hemorrhage

over 6
- life-threatening bleeding in the next 2 weeks = 4%

24
Q

What are options for non-bleeding patients INR over 4 but esp in over 6 (2)

A
  • Withhold 1 or 2 doses of warfarin and repeat until INR under 4
    OR
  • Administer a small dose of vitamin K (1-2.5mg po)
25
Q

What is reversal agent for warfarin? Response time? ADRs?

A

Vitamin K
- IV 6 hours
- Oral (12-24 hours)

IV can cause anaphylactoid reaction
SC can have more erratic absoportion

26
Q

What is the antidote for warfarin (2)

A

Fresh frozen plasma
OR
Recombinant clotting factors

  • for life-threatening bleeding and immediate reversal
27
Q

What does the evidence say when given 1mg of vitamin K with INR 4.5 - 10 vs holding a dose of warfarin
- risk of bleeding?
- risk of thrombosis?

A

Gets to INR under 4 one day faster
- does not reduce risk of bleeding
- does not increase risk of thrombosis

28
Q

What factors can SLOW INR drop after holding 2 doses when INR is over 6 (5)

A
  • Lower weekly warfarin dose (<20mg/week)
  • Age over 65
  • Extreme elevation in INR
  • Decompensated heart failure
  • Active cancer/decreased oral intake
29
Q

When is vitamin K usually given

A

For those with high risk of bleeding and high risk of slow INR decay

30
Q

When is a warfarin dose too high during initiation phase

A

If increasing more than 0.2/day

31
Q

What are the dietary considerations with warfarin

A

No need to stop eating vegetables
- just stay consistent in diet!

Studies: INR stability was better in patients who consumed the highest amount of dietary vit K

  • not therapeutic levels of vit K in green vegetables
32
Q

What are advantages of DOACs compared to warfarin (3)

A
  1. Quick onset
    - no need to overlap with rapid acting parenteral anticoagulant
  2. No need to monitor effect
  3. Fewer drug, disease and lifestyle interactions
33
Q

Challenges of DOACs compared to warfarin (5)

A
  1. Renal elimination (contraindicated in CrCl <30)
  2. Some are dosed BID
  3. Inability to accurately measure drug effect
    - was PE due to drug failure or non-adherence
    - Did patient have an acute bleed?
    - effect of interacting med?
  4. Bleeding management
    - Reversal agent for DOAC is 3600$ vs vitamin K
  5. Cost
    - rivaroxaban after LU code is expensive
34
Q

What is the duration of anticoagulation for acute VTE

A

Min 3 months
- Provoked VTE by a reversible risk factor (surgery)

Possibly indefinitely
- first episode of UNPROVOKED VTE, esp if PE

Likely indefinitely
- 2nd episode of unprovoked VTE
- recall: has a 15% chance of recurrence/year without warfarin and
- 2-3% if they continue therapy

35
Q

What are the options after unprovoked VTE and what % does it reduce recurrent VTE by? (3)

A
  1. Warfarin reduces recurrent VTE by 80-90%
  2. ASA 100mg reduces recurrent VTE by 30%
  3. DOAC reduces recurrent VTE by 70-80%
36
Q

What is preferred in the following special populations
Pregnancy
Pediatrics
Cancer

A

Pregnancy
- LMWH (preferred) and UFH
- do not use warfarin or DOACs

Pediatrics
- UFH and warfarin are mostly used due to enough data

Cancer
- LMWH may be better than warfarin
- newer studies suggest DOACs= LWMH but with inc bleeding risk (except apixaban)

IPFC 3 Midterm 2 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions