Warfarin: uses, appearance and warnings

Warfarin sodium tablets are indicated for: Prophylaxis and treatment of venous thrombosis and its extension, pulmonary embolism (PE). Prophylaxis and treatment of thromboembolic complications associated with atrial fibrillation (AF) and/or cardiac valve replacement. Reduction in the risk of death, recurrent myocardial infarction (MI), and thromboembolic events such as stroke or systemic embolization after myocardial infarction. Limitations of Use Warfarin sodium tablets have no direct effect on an established thrombus, nor does it reverse ischemic tissue damage. Once a thrombus has occurred, however, 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. Warfarin sodium tablets are vitamin K antagonist indicated for: Prophylaxis and treatment of venous thrombosis and its extension, pulmonary embolism. (1) Prophylaxis and treatment of thromboembolic complications associated with atrial fibrillation and/or cardiac valve replacement. (1) Reduction in the risk of death, recurrent myocardial infarction, and thromboembolic events such as stroke or systemic embolization after myocardial infarction. (1) Limitations of Use Warfarin sodium tablets have no direct effect on an established thrombus, nor does it reverse ischemic tissue damage. (1)

Warfarin Sodium Tablets USP, 1 mg are supplied as pink to light pink, oval shaped uncoated scored tablets with debossing ‘761’ and ‘1’ on either side of the breakline on one side and ‘AN’ on the other side. Warfarin Sodium Tablets USP, 2 mg are supplied as lavender to light lavender, oval shaped uncoated scored tablets with debossing ‘762’ and ‘2’ on either side of the breakline on one side and ‘AN’ on the other side. Warfarin Sodium Tablets USP, 2½ mg are supplied as green to light green, oval shaped uncoated scored tablets with debossing ‘763’ and ‘2½’ on either side of the breakline on one side and ‘AN’ on the other side. Warfarin Sodium Tablets USP, 3 mg are supplied as tan to light tan, oval shaped uncoated scored tablets with debossing ‘764’ and ‘3’ on either side of the breakline on one side and ‘AN’ on the other side. Warfarin Sodium Tablets USP, 4 mg are supplied as blue to light blue, oval shaped uncoated scored tablets with debossing ‘765’ and ‘4’ on either side of the breakline on one side and ‘AN’ on the other side. Warfarin Sodium Tablets USP, 5 mg are supplied as peach to light peach, oval shaped uncoated scored tablets with debossing ‘766’ and ‘5’ on either side of the breakline on one side and ‘AN’ on the other side. Warfarin Sodium Tablets USP, 6 mg are supplied as teal to light teal, oval shaped uncoated scored tablets with debossing ‘767’ and ‘6’ on either side of the breakline on one side and ‘AN’ on the other side. …

Tablets Warfarin Sodium Tablets USP, 1 mg are supplied as pink to light pink, oval shaped uncoated scored tablets with debossing ‘761’ and ‘1’ on either side of the breakline on one side and ‘AN’ on the other side. They are available as follows: Bottle of 100 Tablets: NDC 65162-761-10 Bottle of 500 Tablets: NDC 65162-761-50 Bottle of 1000 Tablets: NDC 65162-761-11 Warfarin Sodium Tablets USP, 2 mg are supplied as lavender to light lavender, oval shaped uncoated scored tablets with debossing ‘762’ and ‘2’ on either side of the breakline on one side and ‘AN’ on the other side. They are available as follows: Bottle of 100 Tablets: NDC 65162-762-10 Bottle of 500 Tablets: NDC 65162-762-50 Bottle of 1000 Tablets: NDC 65162-762-11 Warfarin Sodium Tablets USP, 2½ mg are supplied as green to light green, oval shaped uncoated scored tablets with debossing ‘763’ and ‘2½’ on either side of the breakline on one side and ‘AN’ on the other side. They are available as follows: Bottle of 100 Tablets: NDC 65162-763-10 Bottle of 500 Tablets: NDC 65162-763-50 Bottle of 1000 Tablets: NDC 65162-763-11 Warfarin Sodium Tablets USP, 3 mg are supplied as tan to light tan, oval shaped uncoated scored tablets with debossing ‘764’ and ‘3’ on either side of the breakline on one side and ‘AN’ on the other side. They are available as follows: Bottle of 100 Tablets: NDC 65162-764-10 Bottle of 500 Tablets: NDC 65162-764-50 Bottle of 1000 Tablets: NDC 65162-764-11 Warfarin Sodium Tablets USP, 4 mg are supplied as blue to light blue, oval shaped uncoated scored tablets with debossing ‘765’ and ‘4’ on either side of the breakline on one side and ‘AN’ on the other side. They are available as follows: Bottle of 100 Tablets: NDC 65162-765-10 Bottle of 500 Tablets: NDC 65162-765-50 Bottle of 1000 Tablets: NDC 65162-765-11 Warfarin Sodium Tablets USP, 5 mg are supplied as peach to light peach, oval shaped uncoated scored tablets with debossing ‘766’ and ‘5’ on either side of the breakline on one side and ‘AN’ on the other side. They are available as follows: Bottle of 100 Tablets: NDC 65162-766-10 Bottle of 500 Tablets: NDC 65162-766-50 Bottle of 1000 Tablets: NDC 65162-766-11 Warfarin Sodium Tablets USP, 6 mg are supplied as teal to light teal, oval shaped uncoated scored tablets with debossing ‘767’ and ‘6’ on either side of the breakline on one side and ‘AN’ on the other side. …

Warfarin sodium is contraindicated in: Pregnancy Warfarin sodium is contraindicated in women who are pregnant except in pregnant women with mechanical heart valves, who are at high risk of thromboembolism [see Warnings and Precautions (5.7) and Use in Specific Populations (8.1 )] . Warfarin sodium can cause fetal harm when administered to a pregnant woman. Warfarin sodium exposure during pregnancy causes a recognized pattern of major congenital malformations (warfarin embryopathy and fetotoxicity), fatal fetal hemorrhage, and an increased risk of spontaneous abortion and fetal mortality. If warfarin sodium is used during pregnancy or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to a fetus [see Use in Specific Populations (8.1) ] . Warfarin sodium is contraindicated in patients with: Hemorrhagic tendencies or blood dyscrasias Recent or contemplated surgery of the central nervous system or eye, or traumatic surgery resulting in large open surfaces [see Warnings and Precautions (5.8) ] Bleeding tendencies associated with: − Active ulceration or overt bleeding of the gastrointestinal, genitourinary, or respiratory tract − Central nervous system hemorrhage − Cerebral aneurysms, dissecting aorta − Pericarditis and pericardial effusions − Bacterial endocarditis Threatened abortion, eclampsia, and preeclampsia Unsupervised patients with conditions associated with potential high level of non-compliance Spinal puncture and other diagnostic or therapeutic procedures with potential for uncontrollable bleeding Hypersensitivity to warfarin or to any other components of this product (e.g., anaphylaxis) [see Adverse Reactions (6) ] Major regional or lumbar block anesthesia Malignant hypertension Pregnancy, except in women with mechanical heart valves. ( 4 , 5.7 , 8.1 ) Hemorrhagic tendencies or blood dyscrasias. …

Tissue necrosis: Necrosis or gangrene of skin or other tissues can occur, with severe cases requiring debridement or amputation. Discontinue warfarin sodium and consider alternative anticoagulants if necessary. (5.2) Calciphylaxis: Fatal and serious cases have occurred. Discontinue warfarin sodium and consider alternative anticoagulation therapy. ( 5.3 ) Acute kidney injury may occur during episodes of excessive anticoagulation and hematuria. ( 5.4 ) Systemic atheroemboli and cholesterol microemboli: Some cases have progressed to necrosis or death. Discontinue warfarin sodium if such emboli occur. ( 5.5 ) Heparin-induced thrombocytopenia (HIT): Initial therapy with warfarin sodium in HIT has resulted in cases of amputation and death. Warfarin sodium may be considered after platelet count has normalized. ( 5.6) Pregnant women with mechanical heart valves: Warfarin sodium may cause fetal harm; however, the benefits may outweigh the risks. ( 5.7 ) 5.1 Hemorrhage Warfarin sodium can cause major or fatal bleeding. Bleeding is more likely to occur within the first month. Risk factors for bleeding include high intensity of anticoagulation (INR >4.0), age greater than or equal to 65, history of highly variable INRs, history of gastrointestinal bleeding, hypertension, cerebrovascular disease, anemia, malignancy, trauma, renal impairment, certain genetic factors [see Clinical Pharmacology (12.5) ] , certain concomitant drugs [see Drug Interactions (7) ] , and long duration of warfarin therapy. Perform regular monitoring of INR in all treated patients. Those at high risk of bleeding may benefit from more frequent INR monitoring, careful dose adjustment to desired INR, and a shortest duration of therapy appropriate for the clinical condition. However, maintenance of INR in the therapeutic range does not eliminate the risk of bleeding. Drugs, dietary changes, and other factors affect INR levels achieved with warfarin sodium therapy. Perform more frequent INR monitoring when starting or stopping other drugs, including botanicals, or when changing dosages of other drugs [see Drug Interactions (7) ] . Instruct patients about prevention measures to minimize risk of bleeding and to report signs and symptoms of bleeding [see Patient Counseling Information (17) ] . 5.2 Tissue Necrosis Warfarin sodium can cause necrosis and/or gangrene of skin and other tissues, which is an uncommon but serious risk (<0.1%). Necrosis may be associated with local thrombosis and usually appears within a few days of the start of warfarin sodium therapy. In severe cases of necrosis, treatment through debridement or amputation of the affected tissue, limb, breast, or penis has been reported. Careful clinical evaluation is required to determine whether necrosis is caused by an underlying disease. Although various treatments have been attempted, no treatment for necrosis has been considered uniformly effective. Discontinue warfarin sodium therapy if necrosis occurs. Consider alternative drugs if continued anticoagulation therapy is necessary. 5.3 Calciphylaxis Warfarin sodium can cause fatal and serious calciphylaxis or calcium uremic arteriolopathy, which has been reported in patients with and without end-stage renal disease. When calciphylaxis is diagnosed in these patients, discontinue warfarin sodium and treat calciphylaxis as appropriate. Consider alternative anticoagulation therapy. 5.4 Acute Kidney Injury In patients with altered glomerular integrity or with a history of kidney disease, acute kidney injury may occur with warfarin sodium, possibly in relation to episodes of excessive anticoagulation and hematuria [see Use in Specific Populations (8.6 )] . More frequent monitoring of anticoagulation is advised in patients with compromised renal function. 5.5 Systemic Atheroemboli and Cholesterol Microemboli Anticoagulation therapy with warfarin sodium may enhance the release of atheromatous plaque emboli. Systemic atheroemboli and cholesterol microemboli can present with a variety of signs and symptoms depending on the site of embolization. The most commonly involved visceral organs are the kidneys followed by the pancreas, spleen, and liver. Some cases have progressed to necrosis or death. A distinct syndrome resulting from microemboli to the feet is known as “purple toes syndrome.” Discontinue warfarin sodium therapy if such phenomena are observed. Consider alternative drugs if continued anticoagulation therapy is necessary. 5.6 Limb Ischemia, Necrosis, and Gangrene in Patients with HIT and HITTS Do not use warfarin sodium as initial therapy in patients with heparin-induced thrombocytopenia (HIT) and with heparin-induced thrombocytopenia with thrombosis syndrome (HITTS). Cases of limb ischemia, necrosis, and gangrene have occurred in patients with HIT and HITTS when heparin treatment was discontinued and warfarin therapy was started or continued. In some patients, sequelae have included amputation of the involved area and/or death. Treatment with warfarin sodium may be considered after the platelet count has normalized. 5.7 Use in Pregnant Women with Mechanical Heart Valves Warfarin sodium can cause fetal harm when administered to a pregnant woman. While warfarin sodium is contraindicated during pregnancy, the potential benefits of using warfarin sodium may outweigh the risks for pregnant women with mechanical heart valves at high risk of thromboembolism. In those individual situations, the decision to initiate or continue warfarin sodium should be reviewed with the patient, taking into consideration the specific risks and benefits pertaining to the individual patient’s medical situation, as well as the most current medical guidelines. Warfarin sodium exposure during pregnancy causes a recognized pattern of major congenital malformations (warfarin embryopathy and fetotoxicity), fatal fetal hemorrhage, and an increased risk of spontaneous abortion and fetal mortality. …

The following serious adverse reactions to warfarin sodium are discussed in greater detail in other sections of the labeling: Hemorrhage [see Boxed Warning , Warnings and Precautions (5.1) , and Overdosage (10) ] Tissue Necrosis [see Warnings and Precautions (5.2) ] Calciphylaxis [see Warnings and Precautions (5.3) ] Acute Kidney Injury [see Warnings and Precautions (5.4) ] Systemic Atheroemboli and Cholesterol Microemboli [see Warnings and Precautions (5.5) ] Limb Ischemia, Necrosis, and Gangrene in Patients with HIT and HITTS [see Warnings and Precautions (5.6) ] Other Clinical Settings with Increased Risks [see Warnings and Precautions (5.8) ] Other adverse reactions to warfarin sodium include: Immune system disorders: hypersensitivity/allergic reactions (including urticaria and anaphylactic reactions) Vascular disorders: vasculitis Hepatobiliary disorders: hepatitis, elevated liver e …

Concomitant use of drugs that increase bleeding risk, antibiotics, antifungals, botanical (herbal) products, and inhibitors and inducers of CYP2C9, 1A2, or 3A4. ( 7 ) Consult labeling of all concurrently used drugs for complete information about interactions with warfarin sodium or increased risks for bleeding. (7) 7.1 General Information Drugs may interact with warfarin sodium through pharmacodynamic or pharmacokinetic mechanisms. Pharmacodynamic mechanisms for drug interactions with warfarin sodium are synergism (impaired hemostasis, reduced clotting factor synthesis), competitive antagonism (vitamin K), and alteration of the physiologic control loop for vitamin K metabolism (hereditary resistance). Pharmacokinetic mechanisms for drug interactions with warfarin sodium are mainly enzyme induction, enzyme inhibition, and reduced plasma protein binding. …