Anticoagulation competency

Warfarin Interactions With Drugs, Herbals, Foods And Labs Drug-Drug Interactions
Interacting Medication
Adverse Effect
Management
Severity
Mechanism
Concurrent administration
contraindicated. Do not
give within 7 days of
Abciximab (Reopro)
Excessive bleeding
Major Rapid
Additive
anticoagulation
abciximab use unless PT
time is less than or equal
Limit to 2gram/day of
Inhibition of warfarin
Tylenol for no more than a
Acetaminophen
Increased risk of
metabolism or
few days. Monitor INR for
Moderate Delayed
(Tylenol)
bleeding
interference with clotting
larger doses or longer
factor formation
Monitor INR closely with
Increased risk of
Allopurinol (Zyloprim)
addition and withdrawal of Moderate Delayed
bleeding
allopurinol
Concurrent administration
Alteplase (Activase)
Excessive bleeding
contraindicated if PT is
Major Rapid
Additive
anticoagulation
greater than 15 sec.
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management
Severity
Mechanism
Prophylactic 25%
reduction in warfarin dose
Amiodarone
Increased risk of at initiation of amiodarone.
Decreased warfarin
Moderate Delayed
(Cordarone)
bleeding
Monitor INR closely with
metabolism
addition or withdrawal of
amiodarone
Avoid combination if
Inhibition of warfarin
Androgens/Anabolic
Increased risk of
possible. Monitor INR
metabolism and/or direct
Moderate Delayed
Steroids (Drug Class)
bleeding
closely with addition or
effect on coagulation and
withdrawal of androgens.
fibrinolytic systems
Closely monitor INR with
Decreased
addition and withdrawal of
Decreased metabolism of
Antithyroid agents
anticoagulant
antithyroid drugs. May
Moderate Delayed
clotting factors
effectiveness
need increased warfarin
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management
Severity
Mechanism
Not an absolute
contraindication but
should be avoided.
Displacement of warfarin
Increased risk of
Monitor INR and watch for
from albumin, warfarin
Major Delayed
bleeding
signs of bleeding.
metabolism inhibition, and
Consider non-acetylated
gastric erosion
salicylates or Tylenol for
analgesia
Decreased
Monitor INR closely with
Barbiturates (Drug
Increased warfarin
anticoagulant
addition or withdrawal of
Moderate Delayed
metabolism
effectiveness
barbiturates.
Monitor INR closely with
Hypoprothrombinemia
Bismuth subsalicylate
Increased risk of
addition or withdrawal of
Moderate Delayed Displacement of warfarin
(Pepto-Bismol)
bleeding
bismuth subsalicylate.
form albumin
Reassess periodically.
Not recommended for
concomitant use. Monitor
Increased risk of
INR and signs of bleeding
Unknown. Probable
Boldo (Herbal)
Major Delayed
bleeding
if pt continues to take.
antiplatelet effects.
Notify provider prior to
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management
Severity
Mechanism
Monitor for excessive
Calcium Channel
Increased risk of GI bleeding, especially from Moderate Delayed
Additive
Blockers
hemorrhage
the GI tract.
Intense INR monitoring.
Often necessary to
increase the warfarin dose
Decreased
Carbamazepine
at initiation and decrease
Increased warfarin
anticoagulant
Moderate Delayed
(Tegretol)
the warfarin dose at D/C.
metabolism
effectiveness
Stabilization of INR may
require 4-6 weeks after
initiation or D/C.
Decreased
In laxative abusers may
Castor Oil
anticoagulant
lessen response to a
Moderate Not
specified Decreased GI transit time
effectiveness
particular dose
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management Severity
Mechanism
Closely monitor INR.
Cefamandole (Mandol),
Inhibition of platelet
Adjustment of dose is
Cefoperazone
function, decreased
Increased risk of
frequently necessary. Use
(Cefobid), Cefotetan
Moderate Delayed synthesis of vitamin K
bleeding
cephalosporin without
(Cefotan), Moxalatam
dependant clotting
hypoprothrombinemic
factors.
properties.
Monitor INR especially in
first few days after
Competition for
Increased risk of
Celecoxib (Celebrex)
initiating or changing
Moderate Delayed metabolism via CY P450
bleeding
celecoxib. More likely in
2C9 enzymes.
elderly population.
Should not be given with
Decreased warfarin
Cholestyramine
Decreased warfarin warfarin. Use colestipol in
absorption, interferes with
Moderate Delayed
(Questran)
effectiveness
patients who need a bile
enterohepatic
acid sequestrant.
recirculation.
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management Severity
Mechanism
Avoid concomitant use.
Increased risk of
Use alternate H2 blocker.
Decreased warfarin
Cimetidine (Tagamet)
Moderate Delayed
bleeding
Monitor INR frequently
metabolism
until INR is stable.
Monitor INR closely with
Increased risk of
Cisapride (Propulsid)
addition or withdrawal of
Moderate Delayed
bleeding
cisapride
Avoid concomitant use.
Similar chemical structure
Reduced warfarin
Coenzyme Q10 (Herbal)
Decreased INR in
Major Delayed
of coenzyme Q10 and
efficacy
stabilized patients.
vitamin K2
Decreased or
Generally avoid
increased
Contraceptives, Oral
concurrent use. Monitor
Moderate Delayed
anticoagulant
INR closely.
effectiveness
Inhibition of warfarin
Monitor INR closely with
Cotrimoxazole
Increased risk of
metabolism. Displacement
addition and withdrawal of Moderate Delayed
(Bactrim)
bleeding
of warfarin form protein
cotrimoxazole
binding sites.
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management Severity
Mechanism
Caution against taking
Danshen (Salvia Root) Increased risk for
Decreased warfarin
danshen or smoking
Moderate Delayed
(Herbal)
over-anticoagulation
metabolism
danshen cigarettes
anticoagulant effect addition and withdrawal of Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management Severity
Onset Mechanism
Potentiation of
Dong Quai (Herbal)
anticoagulation
Avoid concomitant use
Use combination only
when benefit outweighs
Increased risk of
the risk of bleeding.
Additive effects on
Eptifibatide (Integrilin)
Moderate Delayed
bleeding
Observe patient for
hemostasis
external bleeding and s/s
of internal bleeding.
Monitor for
Decreased
hypercoagulability,
Estrogens
anticoagulant
including recurrent
Moderate Delayed
effectiveness
thrombosis. May require
d/c of estrogen therapy.
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management Severity
Onset Mechanism
Monitor INR closely with
Increased risk of
Fenofibrate (Tricor)
addition and withdrawal of
Moderate Delayed
bleeding
fenofibrate
Concomitant use not
recommended. Monitor INR
Increased risk of
Unknown. Probable
Fenugreek (Herbal)
and s/s of bleeding closely.
Major Delayed
bleeding
coumarin effects.
Do not d/c without notifying
health care providers.
bleeding. Obtain bleeding time Moderate Delayed Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management
Severity
Mechanism
Concomitant use is not
recommended. D/c garlic
10 day prior to elective
Possible additive or
Increased risk of
Garlic (Herbal)
surgery. Get baseline
Major Delayed
synergistic anticoagulant
bleeding
bleeding times prior to
initiating warfarin.
Monitor INR closely.
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management
Severity
Mechanism
Decreased warfarin
Monitor INR closely with
Increased risk of
metabolism. Displacement
Gemfibrozil (Lopid)
addition and withdrawal
Moderate Delayed
bleeding
of warfarin from protein
of gemfibrozil
binding sites.
Baseline PT. Monitor for
s/s of bleeding in patients
Possible additive or
Increased risk of
taking over 4 gram of
Ginger (Herbal)
Moderate Rapid
synergistic anticoagulant
bleeding
dried or 15 gram of raw
ginger root daily prior to
initiating warfarin.
Avoid concomitant use.
Should not be taken with
Possible additive or
Increased risk of
Ginkgo (Herbal)
any anticoagulant.
Major Delayed
synergistic anticoagulant
bleeding
Monitor bleeding time and
s/s of excessive bleeding.
Loss of warfarin
Avoid concomitant use.
Inhibition of platelet
Ginseng (Herbal)
Moderate Delayed
efficacy
Monitor INR closely.
aggregation
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management
Severity
Mechanism
Monitor INR closely with
Glyburide (Diabeta,
Increased risk of addition and withdrawal of Moderate Delayed
Glynase, Micronase)
bleeding
glyburide
Monitor patient closely for
Increased risk of
hypoglycemia. Instruct
Glipizide (Glucotrol)
Moderate Delayed
bleeding
patient on s/s of
hypoglycemia
Amount of green tea
consumed and method of
production affect amount
Reduced warfarin
of vitamin K present.
Antagonism by vitamin K
Green Tea (Herbal)
Moderate Delayed
efficacy
Patients should consume a
in green tea
consistent amount, use a
consistent brand and
method of brewing.
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management
Severity
Mechanism
Influenza Vaccine
Increased risk of
Monitor INR within 1-2
Moderate Delayed
(Flushield, Fluvirin)
bleeding
weeks following vaccine
Excessive bleeding reach aPTT ration just above Moderate Rapid different mechanism Monitor INR closely with
Increased risk of
Lovastatin (Mevacor)
addition and withdrawal of Moderate Delayed
bleeding
lovastatin
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management
Severity
Mechanism
D/c warfarin prior to
initiation. Monitor closely
Increased risk of
for bleeding if used
bleeding and
concurrently. GI bleeds are
Decreased platelet
Low Molecular Weight
hematoma when of particular concern, as is Moderate Rapid function. Decreased
Heparins (Drug Class)
neuraxial
spinal or epidural
coagulation.
anesthesia is
hematoma in patients with
employed
epidural/spinal anesthesia.
This is not fully reflected
by the aPPT.
Monitor INR closely with
Macrolide Antibiotics
Increased risk of
Decreased warfarin
addition and withdrawal of Moderate Delayed
(Drug Class)
bleeding
metabolism
macrolide antibiotics
Avoid concurrent use.
Methyl Salicylate
Increased risk of
Inhibition of warfarin
Topical capsaicin ointment Moderate Delayed
(Topical Preparation)
bleeding
metabolism
is a preferable alternative
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management
Severity
Mechanism
Avoid consumption of
Increased or
mineral oil. May impair
Decreased vitamin K
Mineral Oil
decreased warfarin absorption of vitamin K.
Moderate Unknown absorption. Decreased
effectiveness
May impair absorption of
warfarin absorption.
warfarin.
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management
Severity
Mechanism
Monitor INR closely with
addition and withdrawal of
NSAIDs. Coagulation
Increased risk of
parameters should be
Gastric erosion. Inhibition
NSAIDs (Drug Class)
Moderate Delayed
bleeding
reassessed periodically.
of platelet aggregation.
Be aware of increased
bleeding risk especially
from the GI tract.
Monitor INR closely with
Increased risk of
Decreased warfarin
Omeprazole (Prilosec)
addition and withdrawal of Moderate Delayed
bleeding
metabolism
omeprazole
Increased risk of
Decreased vitamin K
Orlistat (Xenical)
Monitor INR closely
bleeding
absorption
Avoid concomitant use of
Direct damage to GI tract
Increased risk of
papaya extract and
Papaya (Herbal)
Major Unknown leading to increased
bleeding
warfarin. Monitor INR and
bleeding
s/s of bleeding closely.
Transient increased
risk of bleeding at Monitor INR closely during
Displacement of warfarin
initiation. Need for
the 2-3 week interval
from protein binding sites.
Phenytoin (Dilantin)
Moderate Delayed
increased warfarin
following the addition or
Increased warfarin
dosage during
deletion of phenytoin
metabolism.
chronic therapy.
Do not use in patients
Decreased
receiving warfarin except
Phytonadione (Vitamin
Antagonism of warfarin's
anticoagulant
in cased of acute bleeding Moderate Delayed
mechanism of action
effectiveness
due to excessive
anticoagulation
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management
Severity
Mechanism
Propoxyphene
Increased risk of
Monitor INR closely
Moderate
(Darvocet, Darvon)
bleeding
Monitor INR for effect on
anticoagulant response. If
Increased risk of
Decreased warfarin
Ranitidine (Zantac)
INR is unstable consider
Moderate Delayed
bleeding
metabolism
using famotidine or
nizatidine.
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management
Severity
Mechanism
Use concurrently only
when potential benefit
Increased risk of
outweighs the risk.
Additive anticoagulant
Reteplase (Retavase)
Moderate Rapid
bleeding
Observe patient for s/s of
external and internal
bleeding.
decrease in INR.
Generally avoid
concurrent use. Monitor
Inhibition of platelet
INR closely. Watch for
aggregation.
Salicylates (Drug
Increased risk of
signs of bleeding
Moderate Delayed
Displacement of
bleeding
especially in the GI tract. If
anticoagulant from protein
used for analgesia
binding site.
consider using Tylenol.
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management Severity
Onset Mechanism
Monitor INR closely with
addition or withdrawal of
simvastatin. Monitor for
Increased risk of
s/s of myopathy or
bleeding. Increased rhabdomyolysis (muscle
Competition for CY P450
Simvastatin (Zocor)
Moderate Delayed
pain, tenderness, or
3A4 mediated metabolism
rhabdomyolysis.
weakness. Monitor CK
levels and d/c if CK show
marked increase or s/s
develop.
Decreased
Monitor INR closely with
Diuresis-induced
Spironolactone
anticoagulant
addition and withdrawal of Moderate Delayed concentration of clotting
(Aldactone)
effectiveness
spironolactone
Concomitant use not
recommended. Monitor for
symptoms of decreased
warfarin efficacy. Titrate
warfarin upwards only if
patient on consistent dose
St. John's Wort
Reduced warfarin
of St. John's Wort with a
Induction of CY P450 1A2
Major Delayed
(Herbal)
effectiveness
reputable product
containing consistent
amounts of active
ingredients. Do not d/c St.
John's Wort without
notifying health care
provider.
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management Severity
Onset Mechanism
Use combination with
extreme caution. Should
only be done under the
supervision of a
Streptokinase
Increased risk of
physician/pharmacist
Moderate
Additive hemorrhagic risk
(Kabikinase, Streptase)
bleeding
experienced in the use of
both drugs and the
interpretation of the
affected hematologic
parameters.
Monitor INR closely with
Decreased warfarin
Decreased warfarin
Sucralfate (Carafate)
addition and withdrawal of Moderate Delayed
effectiveness
absorption
sucralfate
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management
Severity
Mechanism
Monitor INR closely with
Tetracycline
Increased risk of
the addition and
Antibiotics (Drug
Moderate Delayed
bleeding
withdrawal of tetracycline
antibiotic therapy
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management
Severity
Mechanism
Monitor INR closely with
addition and withdrawal of
thyroid hormone therapy.
Increased metabolism of
Thyroid Hormones
Increased risk of Patients already stabilized Moderate Delayed vitamin K dependant
(Drug Class)
bleeding
on thyroid hormone such
clotting factors
that they are euthyroid will
respond normally to
warfarin therapy.
Increase in the
concentration of the Monitor INR periodically
Inhibition of R-warfarin
R-warfarin
Ticlodipine (Ticlid)
due to large interpatient
Moderate Delayed metabolism. Inhibition of
enantiomer and/or
variability
platelet aggregation.
increased risk of
bleeding
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Adverse Effect
Management Severity
Mechanism
Tricyclic
Decreased warfarin
Increased risk of
Antidepressants (Drug
Closely monitor INR
Moderate
metabolism. Increased
bleeding
warfarin absorption.
Urokinase
Increased risk of
Do not administer with
Moderate
Additive hemorrhagic risk
(Abbokinase)
bleeding
warfarin
Monitor INR closely when
Increased risk of
Vitamin A
large doses of vitamin A
Unknown Unknown
bleeding
are given
Monitor INR closely with
Increased risk of addition and withdrawal of
Vitamin E
Moderate Delayed
bleeding
greater than 300 IU of
vitamin E per day
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Drug-Food Interactions
Interacting Food
Adverse Effect
Management
Severity
Mechanism
Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Drug-Lab Interactions
Interacting Lab
Adverse Effect
Management
Severity
Mechanism
This is not an all inclusive list. Please call your pharmacist for additional details. Warfarin Interactions With Drugs, Herbals, Foods And Labs
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Source: http://www.shmg.org/workfiles/pdf/WarfarinInteractionsWithDrugs.pdf