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May cause major or fatal bleeding; monitor INR regularly. Drugs, dietary changes, and other factors affect INR levels achieved w/ therapy. Instruct patients about prevention measures to minimize risk of bleeding and to report signs/symptoms of bleeding.
Vitamin K-dependent coagulation factor inhibitor
Including Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE):Target INR: 2.5 (INR Range, 2-3) for all treatment durationsDuration of Therapy:DVT/PE Secondary to Transient Risk Factor: 3 monthsUnprovoked DVT/PE: At least 3 months; evaluate risk-benefit ratio of long-term treatment after 3 months of therapy2 Episodes of Unprovoked DVT/PE: Long-term treatment recommended
Target INR: 2.5 (INR Range, 2-3)Duration of Therapy:Persistent/Paroxysmal A-Fib and High Risk of Stroke: Long-term treatment recommendedPersistent/Paroxysmal A-Fib and Intermediate Risk of Ischemic Stroke: Long-term treatment recommendedA-Fib and Mitral Stenosis: Long-term treatment recommendedA-Fib and Prosthetic Heart Valves: Long-term treatment recommended; target INR may be increased and aspirin (ASA) added depending on valve type and position, and on patient factors
Bileaflet Mechanical Valve/Medtronic Hall Tilting Disk Valve in the Aortic Position in Sinus Rhythm and w/o Left Atrial Enlargement:Target INR: 2.5 (INR Range, 2-3)Tilting Disk Valves and Bileaflet Mechanical Valves in the Mitral Position: Target INR: 3 (INR Range, 2.5-3.5)Caged Ball or Caged Disk Valves: Target INR: 3 (INR Range, 2.5-3.5)Bioprosthetic Valve in the Mitral Position: Target INR: 2.5 (INR Range, 2-3) for the first 3 months after valve insertion. If additional risk factors for thromboembolism present, target INR 2.5 (INR Range, 2-3)
High Risk Patients w/ MI:Treat w/ combined moderate-intensity (INR, 2-3) warfarin plus low-dose ASA (≤100 mg/day) for at least 3 months after MI
Unknown Etiology:Use a moderate dose regimen (INR, 2-3)
Expected Maint Daily Doses Based on CYP2C9 and VKORC1 Genotypes:VKORC1-GG:CYP2C9 *1/*1: 5-7mgCYP2C9 *1/*2: 5-7mgCYP2C9 *1/*3: 3-4mgCYP2C9 *2/*2: 3-4mg CYP2C9 *2/*3: 3-4mg CYP2C9 *3/*3: 0.5-2mgVKORC1-AG:CYP2C9 *1/*1: 5-7mg CYP2C9 *1/*2: 3-4mg CYP2C9 *1/*3: 3-4mg CYP2C9 *2/*2: 3-4mg CYP2C9 *2/*3: 0.5-2mg CYP2C9 *3/*3: 0.5-2mgVKORC1-AA:CYP2C9 *1/*1: 3-4mg CYP2C9 *1/*2: 3-4mg CYP2C9 *1/*3: 0.5-2mg CYP2C9 *2/*2: 0.5-2mg CYP2C9 *2/*3: 0.5-2mg CYP2C9 *3/*3: 0.5-2mgCYP2C9 *1/*3, *2/*2, *2/*3, and *3/*3: May require more prolonged time (>2-4 weeks) to achieve max INR effectIf CYP2C9 and VKORC1 Genotypes Are Unknown: Initial: 2-5mg qdMaint: 2-10mg qd
Mitral Stenosis/Valvular Disease Associated w/ A-Fib:Use a moderate dose regimen (INR, 2-3)
From Heparin:Conversion may begin concomitantly w/ heparin therapy or may be delayed 3-6 days.Continue full dose heparin therapy and overlap warfarin therapy w/ heparin for 4-5 days; may d/c heparin once warfarin has produced the desired therapeutic response as determined by INR.Patients receiving both heparin and warfarin should have INR monitoring at least:- Five hrs after the last IV bolus heparin dose, or- Four hrs after cessation of continuous IV heparin infusion, or- Twenty-four hrs after the last SQ heparin injWarfarin may increase the aPTT test, even in the absence of heparin; severe elevation (>50 sec) in aPTT w/ INR in desired range has been identified as an indication of increased risk of postoperative hemorrhageFrom Other Anticoagulants:Consult the labeling of other anticoagulants for conversion instructions
Adequate and well-controlled studies have not been conducted in any pediatric population; optimum dosing and safety/efficacy unknown. Pediatric use is based on adult data and recommendations, and available limited pediatric data
ElderlyElderly/Debilitated: Consider lower initial and maint dosesOther Important ConsiderationsAsian Patients: Consider lower initial and maint dosesTreatment During Dentistry or Surgery: Some dental or surgical procedures may necessitate an interruption or change in dose. Determine the INR immediately prior to any procedure
Oral route (Coumadin, Jantoven) or IV route (Coumadin)CoumadinIV dose is the same as oral dose.IV:Reconstitute vial w/ 2.7mL of sterile water for inj; resulting yield is 2.5mL of a 2mg/mL sol.After reconstitution, administer as a slow bolus inj into a peripheral vein over 1-2 min.Reconstituted sol is stable for 4 hrs at room temperature; discard any unused sol.
Inj: (Coumadin) 5mg; Tab: (Coumadin, Jantoven) 1mg*, 2mg*, 2.5mg*, 3mg*, 4mg*, 5mg*, 6mg*, 7.5mg*, 10mg* *scored
Pregnancy, except in pregnant women w/ mechanical heart valves, who are at high risk of thromboembolism. Hemorrhagic tendencies or blood dyscrasias. Recent or contemplated surgery of the CNS, eye, or traumatic surgery resulting in large open surfaces. Bleeding tendencies associated w/ active ulceration or overt bleeding of GI/genitourinary/respiratory tract, CNS hemorrhage, cerebral aneurysms, dissecting aorta, pericarditis and pericardial effusions, or bacterial endocarditis. Threatened abortion, eclampsia, and preeclampsia. Unsupervised patients w/ conditions associated w/ potential high level of noncompliance. Spinal puncture and other diagnostic/therapeutic procedures w/ potential for uncontrollable bleeding. Hypersensitivity to warfarin or to any other components of the medication (eg, anaphylaxis). Major regional, lumbar block anesthesia. Malignant HTN.
Has no direct effect on established thrombus, nor does it reverse ischemic tissue damage; once a thrombus has occurred, the goals of anticoagulant treatment are to prevent further extension of the formed clot and to prevent secondary thromboembolic complications that may result in serious and possibly fatal sequelae. INR >4 provides no additional therapeutic benefit in most patients and is associated w/ higher risk of bleeding. Bleeding is more likely to occur w/in the 1st month; patients at high risk of bleeding may benefit from more frequent INR monitoring, careful dose adjustment to desired INR, and a shortest duration of therapy. Has a narrow therapeutic range (index) and its action may be affected by endogenous factors, other drugs, and dietary vitamin K. Determine the INR daily after initial dose administration until INR results stabilize in the therapeutic range; after stabilization, perform INR monitoring based on the clinical situation (acceptable interval 1-4 weeks). Risk of necrosis and/or gangrene of skin and other tissues; d/c if necrosis occurs and consider alternative therapy. May enhance the release of atheromatous plaque emboli, and systemic atheroemboli and cholesterol microemboli may occur. D/C if distinct syndrome resulting from microemboli to the feet ("purple toes syndrome") occurs and consider alternative therapy. Do not use as initial therapy w/ heparin-induced thrombocytopenia (HIT) and w/ heparin-induced thrombocytopenia w/ thrombosis syndrome (HITTS); limb ischemia, necrosis, and gangrene reported when heparin was discontinued and warfarin started or continued. Can cause fetal harm in pregnant women. Increased risks of therapy in patients w/ moderate-severe hepatic impairment, infectious diseases/disturbances of intestinal flora, indwelling catheter, severe/moderate HTN, deficiency in protein C-mediated anticoagulant response, polycythemia vera, vasculitis, or diabetes mellitus, or who are undergoing eye surgery. Caution in elderly. Caution w/ hepatic impairment; can potentiate the response to warfarin.
Hemorrhage, necrosis of the skin and other tissues, systemic atheroemboli, cholesterol microemboli, hypersensitivity/allergic reactions, vasculitis, hepatitis, elevated liver enzymes, N/V, diarrhea, rash, dermatitis, tracheal/tracheobronchial calcifications, chills.
Inhibitors of CYP2C9, 1A2, and/or 3A4 may increase effect (increase INR) by increasing exposure of warfarin. Inducers of CYP2C9, 1A2, and/or 3A4 may decrease effect (decrease INR) by decreasing exposure of warfarin. Increased risk of bleeding w/ anticoagulants (argatroban, bivalirudin, heparin), antiplatelet agents (ASA, cilostazol, clopidogrel), NSAIDs (celecoxib, diclofenac, diflunisal), and serotonin reuptake inhibitors (eg, citalopram, desvenlafaxine, duloxetine). Changes in INR reported w/ antibiotics or antifungals; closely monitor INR when starting or stopping any antibiotics or antifungals. Perform more frequent INR monitoring when starting or stopping botanicals; some botanicals (eg, garlic, Ginkgo biloba) may cause additive anticoagulant effects, while some botanicals (eg, coenzyme Q10, St. John's wort, ginseng) may decrease effects. Some botanicals and foods can interact w/ warfarin through CYP450 interactions (eg, echinacea, grapefruit juice, ginkgo, goldenseal, St. John's wort). Cholestatic hepatitis has been associated w/ coadministration of warfarin and ticlopidine. Perform more frequent INR monitoring when starting or stopping other drugs, including botanicals, or when changing dosages of other drugs, including drugs intended for short-term use (eg, antibiotics, antifungals, corticosteroids).
Pregnancy: Contraindicated in women who are pregnant except in pregnant women w/ mechanical heart valves, who are at high risk of thromboembolism, and for whom benefits may outweigh risks. Can cause fetal harm. Crosses the placenta; concentrations in fetal plasma approach the maternal values.Lactation: Warfarin was not present in human milk from mothers treated w/ warfarin from a limited published study. Caution in nursing; monitor breastfeeding infants for bruising or bleeding.Reproductive Potential: Verify pregnancy status of females of reproductive potential prior to initiating therapy. Females of reproductive potential should use effective contraception during treatment and for at least 1 month after the final dose of therapy.
Vitamin K-dependent coagulation factor inhibitor; inhibits the synthesis of vitamin K-dependent clotting factors, which include Factors II, VII, IX, and X, and the anticoagulant proteins C and S. Thought to interfere w/ clotting factor synthesis by inhibition of the C1 subunit of the vitamin K epoxide reductase enzyme complex, thereby reducing the regeneration of vitamin K1 epoxide.
Absorption: (PO) Complete; Tmax=4 hrs. Distribution: Vd=0.14L/kg; plasma protein binding (99%); crosses placenta. Metabolism: Hepatic via CYP2C9, 2C19, 2C8, 2C18, 1A2, 3A4; hydroxylation (major), reduction. Elimination: Urine (≤92%, metabolites); T1/2=1 week.
Assess for risk factors for bleeding (eg, INR>4, age ≥65 yrs, history of highly variable INR, history of GI bleeding, HTN, cerebrovascular disease, malignancy, anemia, trauma, renal impairment, certain genetic factors, long duration of warfarin therapy), factors affecting INR (eg, diarrhea, hepatic disorders, poor nutritional state, steatorrhea, vitamin K deficiency, increased vitamin K intake, hereditary warfarin resistance), pregnancy/nursing status, other conditions where treatment is contraindicated or cautioned, and possible drug interactions. Assess INR. Obtain platelet counts in patients w/ HIT or HITTS.
Monitor for signs/symptoms of bleeding, necrosis/gangrene of skin and other tissues, systemic atheroemboli, cholesterol microemboli, "purple toes syndrome," and other adverse reactions. For patients receiving long-term anticoagulant treatment, periodically reassess risk-benefit ratio of continuing such treatment. Perform regular INR monitoring.
Instruct to inform physician if patient falls often as this may increase risk for complications. Counsel to maintain strict adherence to dosing regimen. Advise not to start or stop other medications, including salicylates (eg, ASA, topical analgesics), OTC drugs, or herbal medications, except on advice of physician. Instruct to inform physician if pregnancy is suspected (to discuss pregnancy planning) or if considering breastfeeding. Counsel to avoid any activity or sport that may result in traumatic injury. Instruct that regular PT tests and visits to physician are required during therapy. Advise patient to carry ID card stating drug is being taken. Instruct to eat a normal, balanced diet to maintain consistent intake of vitamin K and to avoid drastic changes in diet, such as eating large amounts of leafy, green vegetables. Advise to take ud. Advise to immediately report unusual bleeding or symptoms or any serious illness, such as severe diarrhea, infection, or fever. Inform that anticoagulant effects may persist for about 2-5 days after discontinuation.
Tab: (Coumadin) 15-30°C (59-86°F). Protect from light and moisture. (Jantoven) 20-25°C (68-77°F); excursions permitted at 15-30°C (59-86°F). Protect from light and moisture. Inj: (Coumadin) 15-30°C (59-86°F). Protect from light. Use reconstituted sol w/in 4 hrs; do not refrigerate. Discard any unused sol.