Pharm
Warfarin Protocol
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Warfarin Protocol
, Coumadin Protocol, Warfarin Reversal, Coumadin Reversal
See Also
Warfarin
Warfarin Drug Interactions
Warfarin Protocol for the Perioperative Period
Anticoagulation in Thromboembolism
Anticoagulation in Atrial Fibrillation
Anticoagulation after Heart Valve Replacement
Rivaroxaban
(
Xarelto
)
Dabigatran
(
Pradaxa
)
Indications
Anticoagulation in Thromboembolism
Anticoagulation in Atrial Fibrillation
Anticoagulation after Heart Valve Replacement
Management
Gene
ral Measures
Take
Warfarin
at the same time everyday
Evening dosing allows for dose modification on the same day as INR results
Medical providers should keep wafarin
Drug Interaction
s in mind when prescribing new medications
Keep diet consistent in
Vitamin K
sources (esp. green leafy vegetables)
Management
INR variability
See
Warfarin Drug Interactions
Vitamin K
supplementation significantly helps stabilize INR levels
Vitamin K
100-150 mcg orally daily
(2007) Blood 109: 2419-33 [PubMed]
Medical conditions that increase INR levels
Hyperthyroidism
Diarrhea
Fever
Congestive Heart Failure
Liver
Disease
Medical conditions that decrease INR levels
Hypothyroidism
Protocol
Starting
Warfarin
in elderly inpatients
Gene
ral
Safe (no patient had an INR >4)
Therapeutic INR achieved within 6-7 days
Initial Dose: 4 mg daily for first 3 days
Dosing protocol after day 3 based on daily INR
INR <1.3:
Warfarin
5 mg
INR 1.3-1.4:
Warfarin
4 mg
INR 1.5-1.6:
Warfarin
3 mg
INR 1.7-1.8:
Warfarin
2 mg
INR 1.9-2.4:
Warfarin
1 mg
INR >2.4: Hold
Warfarin
, check INR daily
References
Siguret (2005) Am J Med 118:137 [PubMed]
Protocol
Starting
Warfarin
in general patients
Indications for starting with concurrent
Heparin
(
Lovenox
)
Thrombophilic state (e.g. known
Protein C Deficiency
)
Thromboembolism
(DVT, PE) within last 3 months
Atrial Fibrillation
with
Cerebrovascular Accident
within last 3 months
Atrial Fibrillation
with
CHADS2-VASc Score
>6
Mechanical Heart Valve
patients (depending on valve)
Indications for starting
Warfarin
without
Heparin
Chronic stable
Atrial Fibrillation
Precautions
Do not use
DOAC
(e.g.
Rivaroxaban
) for bridging to
Warfarin
(use
Lovenox
or similar
LMWH
instead)
When starting
DOAC
, may stop
Warfarin
and start
DOAC
without overlap
Exception
Transitioning from
DOAC
to
Warfarin
may warrant overlapping until
Warfarin
near therapeutic
In all other cases,
LMWH
(e.g.
Lovenox
) is the standard for bridging
Warfarin
References
(2019) Presc Lett 26(2):9-10
Starting dose of
Warfarin
Standard dose: 5 mg orally daily
Anticipate therapeutic by day 4-5
High Dose: 10 mg daily for 2 days, then drop to standard dosing
Indicated for urgency to reach therapeutic level
Consider for young patients with
Thromboembolism
Avoid in chronic
Atrial Fibrillation
(no urgency to get to level)
Study: 10 mg start was therapeutic 1.4 days earlier
Kovacs (2003) Ann Intern Med 138:714-9 [PubMed]
Low dose: 2.5 mg orally daily (or use 4 mg protocol as described above)
Elderly, frail or malnourished
Serious liver disease
High risk of bleeding
Serious comorbidity
Significant warfarin
Drug Interaction
Protocol
Monitor daily INR (typically starting at day 3-4)
Stop
Heparin
when 2 consecutive INRs therapeutic
Monitor INR 2-3 times per week for 1-2 weeks
Monitor INR every 2 weeks and then ecery 4 weeks when stable
Consider less frequent monitoring in stable patients
Indications
Stable INR without
Warfarin
dose change for 12 weeks
Compliant patient, without other
Bleeding Diathesis
or serious comorbidity
Protocol
Consider spacing monitoring of INR to every 12 weeks
References
Schulman (2011) Ann Intern Med 155(10):653-9 [PubMed]
Protocol
Adjust
Warfarin
(based on INR 2 to 3)
See
Warfarin
for other target INR indications
INR less than 2
Increase weekly
Warfarin
dose by 5 to 20%
INR 3 to 3.5
Decrease weekly
Warfarin
dose by 5 to 15% or
Maintain same dose and recheck in 7 days
Banet (2003) Chest 123:499-503 [PubMed]
INR 3.6 to 5.0
Consider withholding one
Warfarin
dose
Decrease weekly
Warfarin
dose by 10 to 15%
INR 5.0 to 10.0
Withhold 1 to 2
Warfarin
doses
Decrease weekly
Warfarin
dose by 10 to 20%
Indications for
Vitamin K
Bleeding or high bleeding risk:
Vitamin K
1.0 to 2.5 mg orally for 1 dose
Surgery in 24 hours:
Vitamin K
2 to 4 mg orally x1 dose
INR exceeds 10.0
Hold
Warfarin
Vitamin K
2.5 to 5 mg orally for 1 dose
Monitor INR daily and consider repeating
Vitamin K
Anticipate significantly lower INR within 24-48 hours
Protocol
Mild to moderate bleeding risk (INR >5-10)
Hold
Warfarin
per protocols above
Vitamin K
Mild bleeding:
Vitamin K
2.5 mg orally
Moderate-severe bleeding:
Vitamin K
5-10 mg orally or IV
Oral route is preferred in all but cases of threatened life or limb
Oral
Vitamin K
has consistent absorption with excellent efficacy
Intravenous
Vitamin K
risks
Anaphylaxis
reaction with infusion rates faster than 15-30 min
Protocol
Serious or Life-threatening bleeding (esp. INR >20)
Replace
Clotting Factor
s (first-line)
Prothrombin Complex Concentrate
4 (
PCC4
,
Kcentra
or outside U.S.
Octaplex
,
Beriplex
)
Preferred if available
FFP-like serum extract that is 25 fold more potent than FFP
Formulation in United States was
PCC3
(without Factor 7) until 2013
Cost is 20 times that of the $250 FFP dose (but faster acting and fewer reactions than FFP)
Avoid in DIC
Dose: 50 Units/kg
Fresh Frozen Plasma
(FFP)
Indicated if PCC is not available
Fresh Frozen Plasma
(FFP) 15 ml/kg (roughly 1 to 1.5 liters for most patients)
Typical empiric adult dose: FFP 4 units
INR of
Fresh Frozen Plasma
is 1.7
Do not expect INR to drop below 1.6 following FFP administration
Each FFP unit replaces 5% of
Clotting Factor
s
Anticipate 45 minutes to thaw FFP and 6 hours to completely transfuse the full 4 unit dose
Factor Eight Inhibitor Bypass Activity (FEIBA)
Similar mechanism and components to PCC
Older regimens (not recommended)
Factor VII
a replacement is no longer recommended
Reverse
Warfarin
effect
Vitamin K
5-10 mg by slow IV infusion (do not use subcutaneous dosing due to inconsistent absorption)
Anticipate
Warfarin
resistance after dose
Avoid in
Valve Replacement
Anaphylaxis
risk to IV
Vitamin K
is reduced with newer preparations from prior 3 events per 100,000
Anticipate 16 hour delay in effect
Consider repeat INR at that time
Consider repeating
Vitamin K
at 12 hours
References
(2013) Presc Lett 20(10): 57
Lex and Orman in Majoewsky (2013) EM:Rap 13(4): 4-5
Dosing Adjustment
Decreased Dosing
Decrease Dosing by 20% (27.5 mg per week)
Warfarin
2.5 mg PO on Monday, Wednesday, Friday
Warfarin
5 mg PO all other days
Decrease Dosing by 15% (30 mg per week)
Warfarin
2.5 mg PO on Monday and Friday
Warfarin
5 mg PO all other days
Decrease Dosing by 5% (32.5 mg per week)
Warfarin
2.5 mg PO on Monday
Warfarin
5 mg PO all other days
Dosing Adjustments
Standard Dosing
Warfarin
5 mg PO qd (35 mg per week)
Dosing Adjustments
Increased Dosing
Increase Dosing by 5% (37.5 mg per week)
Warfarin
7.5 mg PO on Monday
Warfarin
5 mg PO all other days
Increase Dosing by 15% (40 mg per week)
Warfarin
7.5 mg PO on Monday and Friday
Warfarin
5 mg PO all other days
Increase Dosing by 20% (42.5 mg per week)
Warfarin
7.5 mg PO on Monday, Wednesday, Friday
Warfarin
5 mg PO all other days
Resources
Point of Care Guide by Mark Ebell, MD
http://www.aafp.org/20050515/pocform.html
References
Ansell (2001) Chest 119(1 Suppl): 22S-38S [PubMed]
Crowther (2000) Lancet 356:1551-3 [PubMed]
Horton (1999) Am Fam Physician [PubMed]
Holbrook (2012) Chest 141(2 Suppl):e152S-84S [PubMed]
Gage (2000) Am J Med 109:484 [PubMed]
Wigle (2019) Am Fam Physician 100(7): 426-34 [PubMed]
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