ResoundingHealth
Search
  
Basic Drug Info
Drug Name:Warfarin Sodium
Manufacturer:Genpharm, L.P.
Other Info:

Medicines are sometimes prescribed for purposes not mentioned in a Medication Guide.

Do not use WARFARIN for a condition for which it was not prescribed.

Do not give WARFARIN to other people, even if they have the same condition.

It may harm them.This Medication Guide summarizes the most important information about WARFARIN.

If you would like more information, talk with your healthcare provider.

You can ask your healthcare provider or pharmacist for information about WARFARIN that was written for healthcare professionals.If you would like more information, call1-866-436-9155Rx onlyWARFARIN is distributed by:Genpharm, L.P.Napa, CA 94558This Medication Guide has been approved by the U.S.

Food and Drug Administration.This leaflet was prepared by:Genpharm Inc.85 Advance RoadEtobicoke, OntarioM8Z 2S6Issue date: November 2006



Clinical Trials:


Indications and Usage
Warfarin sodium tablets are indicated for the prophylaxis and/or treatment of venous thrombosis and its extension, and pulmonary embolism.Warfarin sodium tablets are indicated for the prophylaxis and/or treatment of the thromboembolic complications associated with atrial fibrillation and/or cardiac valve replacement.Warfarin sodium tablets are indicated to reduce the risk of death, recurrent myocardial infarction, and thromboembolic events such as stroke or systemic embolization after myocardial infarction.
Venous Thrombosis -- The formation or presence of a blood clot (THROMBUS) within a vein.

Pulmonary Embolism -- Blocking of the PULMONARY ARTERY or one of its branches by an EMBOLUS.

Complication -- Any disease or disorder that occurs during the course of (or because of) another disease.

Complication Aspects -- Used with diseases to indicate conditions that co-exist or follow, i.e., co-existing diseases, complications, or sequelae.

Atrial Fibrillation -- Abnormal cardiac rhythm that is characterized by rapid, uncoordinated firing of electrical impulses in the upper chambers of the heart (HEART ATRIA). In such case, blood cannot be effectively pumped into the lower chambers of the heart (HEART VENTRICLES). It is caused by abnormal impulse generation.

Myocardial Infarction -- NECROSIS of the MYOCARDIUM caused by an obstruction of the blood supply to the heart (CORONARY CIRCULATION).

Cerebrovascular accident -- sudden neurologic impairment due to a cerebrovascular disorder, either an arterial occlusion or an intracranial hemorrhage.

Contraindications

Anticoagulation is contraindicated in any localized or general physical condition or personal circumstance in which the hazard of hemorrhage might be greater than the potential clinical benefits of anticoagulation, such as:Pregnancy:Warfarin sodium tablets are contraindicated in women who are or may become pregnant because the drug passes through the placental barrier and may cause fatal hemorrhage to the fetus in utero.

Furthermore, there have been reports of birth malformations in children born to mothers who have been treated with warfarin during pregnancy.Embryopathy characterized by nasal hypoplasia with or without stippled epiphyses (chondrodysplasia punctata) has been reported in pregnant women exposed to warfarin during the first trimester.

Central nervous system abnormalities also have been reported, including dorsal midline dysplasia characterized by agenesis of the corpus callosum, Dandy-Walker malformation, and midline cerebellar atrophy.

Ventral midline dysplasia, characterized by optic atrophy, and eye abnormalities have been observed.

Mental retardation, blindness, and other central nervous system abnormalities have been reported in association with second and third trimester exposure.

Although rare, teratogenic reports following in utero exposure to warfarin include urinary tract anomalies such as single kidney, asplenia, anencephaly, spina bifida, cranial nerve palsy, hydrocephalus, cardiac defects and congenital heart disease, polydactyly, deformities of toes, diaphragmatic hernia, corneal leukoma, cleft palate, cleft lip, schizencephaly, and microcephaly.Spontaneous abortion and still birth are known to occur and a higher risk of fetal mortality is associated with the use of warfarin.

Low birth weight and growth retardation have also been reported.Women of childbearing potential who are candidates for anticoagulant therapy should be carefully evaluated and the indications critically reviewed with the patient.

If the patient becomes pregnant while taking this drug, she should be apprised of the potential risks to the fetus, and the possibility of termination of the pregnancy should be discussed in light of those risks.Hemorrhagic tendencies or blood dyscrasias.Recent or contemplated surgery of: (1) central nervous system; (2) eye; (3) traumatic surgery resulting in large open surfaces.Bleeding tendencies associated with active ulceration or overt bleeding of: (1) gastrointestinal, genitourinary or respiratory tracts; (2) cerebrovascular hemorrhage; (3) aneurysms-cerebral, dissecting aorta; (4) pericarditis and pericardial effusions; (5) bacterial endocarditis.Threatened abortion, eclampsia and preeclampsia.Inadequate laboratory facilities.Unsupervised patients with senility, alcoholism, or psychosis or other lack of patient cooperation.Spinal puncture and other diagnostic or therapeutic procedures with potential for uncontrollable bleeding.Miscellaneous: major regional, lumbar block anesthesia, malignant hypertension and known hypersensitivity to warfarin or to any other components of this product.
Dysplasia -- (dis-PLAY-zha) Cells that look abnormal under a microscope but are not cancer.

Dandy-Walker Syndrome -- A congenital abnormality of the central nervous system marked by failure of the midline structures of the cerebellum to develop, dilation of the fourth ventricle, and upward displacement of the transverse sinuses, tentorium, and torcula. Clinical features include occipital bossing, progressive head enlargement, bulging of anterior fontanelle, papilledema, ataxia, gait disturbances, nystagmus, and intellectual compromise. (From Menkes, Textbook of Child Neurology, 5th ed, pp294-5)

Optic Atrophy -- Atrophy of the optic disk which may be congenital or acquired. This condition indicates a deficiency in the number of nerve fibers which arise in the RETINA and converge to form the OPTIC DISK; OPTIC NERVE; OPTIC CHIASM; and optic tracts. GLAUCOMA; ISCHEMIA; inflammation, a chronic elevation of intracranial pressure, toxins, optic nerve compression, and inherited conditions (see OPTIC ATROPHIES, HEREDITARY) are relatively common causes of this condition.

Blind Vision -- The inability to see or the loss or absence of perception of visual stimuli. This condition may be the result of EYE DISEASES; OPTIC NERVE DISEASES; OPTIC CHIASM diseases; or BRAIN DISEASES affecting the VISUAL PATHWAYS or OCCIPITAL LOBE.

Cranial nerve palsies --

Hydrocephalus -- Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, INTRACRANIAL HYPERTENSION; HEADACHE; lethargy; URINARY INCONTINENCE; and ATAXIA (and in infants macrocephaly). This condition may be caused by obstruction of cerebrospinal fluid pathways due to neurologic abnormalities, INTRACRANIAL HEMORRHAGES; CENTRAL NERVOUS SYSTEM INFECTIONS; BRAIN NEOPLASMS; CRANIOCEREBRAL TRAUMA; and other conditions. Impaired resorption of cerebrospinal fluid from the arachnoid villi results in a communicating form of hydrocephalus. Hydrocephalus ex-vacuo refers to ventricular dilation that occurs as a result of brain substance loss from CEREBRAL INFARCTION and other conditions.

Congenital heart disease -- imperfections or malformations of the heart, existing at, and usually before, birth regardless of their causation.

SCHIZENCEPHALY --

Spontaneous abortion -- Expulsion of the product of FERTILIZATION before completing the term of GESTATION and without deliberate interference.

Stillbirth -- A natural loss of the products of conception.

Growth retardation -- Growth retardation: Decreased rate of growth in the individual or in an affected joint or extremity. An example of the latter is micrognathia in Juvenile Rheumatoid Arthritis.

Hematological Disease -- Disorders of the blood and blood forming tissues.

Bleeding tendency --

Ulcer -- A lesion on the surface of the skin or a mucous surface, produced by the sloughing of inflammatory necrotic tissue.

Pericarditis -- Inflammation of the PERICARDIUM from various origins, such as infection, neoplasm, autoimmune process, injuries, or drugs-induced. Pericarditis usually leads to PERICARDIAL EFFUSION, or CONSTRICTIVE PERICARDITIS.

Bacterial Endocarditis -- Inflammation of the ENDOCARDIUM caused by BACTERIA that entered the bloodstream. The strains of bacteria vary with predisposing factors, such as CONGENITAL HEART DEFECTS; HEART VALVE DISEASES; HEART VALVE PROSTHESIS IMPLANTATION; or intravenous drug use.

Threatened abortion -- UTERINE BLEEDING from a GESTATION of less than 20 weeks without any CERVICAL DILATATION. It is characterized by vaginal bleeding, lower back discomfort, or midline pelvic cramping and a risk factor for MISCARRIAGE.

Eclampsia -- Onset of HYPERREFLEXIA; SEIZURES; or COMA in a previously diagnosed pre-eclamptic patient (PRE-ECLAMPSIA).

Pre-Eclampsia -- A complication of PREGNANCY, characterized by a complex of symptoms including maternal HYPERTENSION and PROTEINURIA with or without pathological EDEMA. Symptoms may range between mild and severe. Pre-eclampsia usually occurs after the 20th week of gestation, but may develop before this time in the presence of trophoblastic disease.

Malignant Hypertension -- A condition of markedly elevated BLOOD PRESSURE with DIASTOLIC PRESSURE usually greater than 120 mm Hg. Malignant hypertension is characterized by widespread vascular damage, PAPILLEDEMA, retinopathy, HYPERTENSIVE ENCEPHALOPATHY, and renal dysfunction.

Hypersensitivity -- Altered reactivity to an antigen, which can result in pathologic reactions upon subsequent exposure to that particular antigen.

Warnings

The most serious risks associated with anticoagulant therapy with warfarin sodium are hemorrhage in any tissue or organ5 (see  BLACK BOX WARNING) and, less frequently (<0.1%), necrosis and/or gangrene of skin and other tissues.

Hemorrhage and necrosis have in some cases been reported to result in death or permanent disability.

Necrosis appears to be associated with local thrombosis and usually appears within a few days of the start of anticoagulant therapy.

In severe cases of necrosis, treatment through debridement or amputation of the affected tissue, limb, breast or penis has been reported.

Careful diagnosis is required to determine whether necrosis is caused by an underlying disease.

Warfarin therapy should be discontinued when warfarin is suspected to be the cause of developing necrosis and heparin therapy may be considered for anticoagulation.

Although various treatments have been attempted, no treatment for necrosis has been considered uniformly effective.

See below for information on predisposing conditions.

These and other risks associated with anticoagulant therapy must be weighed against the risk of thrombosis or embolization in untreated cases.It cannot be emphasized too strongly that treatment of each patient is a highly individualized matter.

Warfarin sodium, a narrow therapeutic range (index) drug, may be affected by factors such as other drugs and dietary Vitamin K.

Dosage should be controlled by periodic determinations of prothrombin time (PT)/lnternational Normalized Ratio (INR) or other suitable coagulation tests.

Determinations of whole blood clotting and bleeding times are not effective measures for control of therapy.

Heparin prolongs the one-stage PT.

When heparin and warfarin are administered concomitantly, refer below to CONVERSION FROM HEPARIN THERAPY for recommendations.Caution should be observed when warfarin sodium is administered in any situation or in the presence of any predisposing condition where added risk of hemorrhage, necrosis, and/or gangrene is present.Anticoagulation therapy with warfarin sodium may enhance the release of atheromatous plaque emboli, thereby increasing the risk of complications from systemic cholesterol microembolization, including the "purple toes syndrome".

Discontinuation of warfarin sodium therapy is recommended when such phenomena are observed.

Systemic atheroemboli and cholesterol microemboli can present with a variety of signs and symptoms including purple toes syndrome, livedo reticularis, rash, gangrene, abrupt and intense pain in the leg, foot, or toes, foot ulcers, myalgia, penile gangrene, abdominal pain, flank or back pain, hematuria, renal insufficiency, hypertension, cerebral ischemia, spinal cord infarction, pancreatitis, symptoms simulating polyarteritis, or any other sequelae of vascular compromise due to embolic occlusion.

The most commonly involved visceral organs are the kidneys followed by the pancreas, spleen, and liver.

Some cases have progressed to necrosis or death.Purple toes syndrome is a complication of oral anticoagulation characterized by a dark, purplish or mottled color of the toes, usually occurring between 3 to 10 weeks, or later, after the initiation of therapy with warfarin or related compounds.

Major features of this syndrome include purple color of plantar surfaces and sides of the toes that blanches on moderate pressure and fades with elevation of the legs; pain and tenderness of the toes; waxing and waning of the color over time.

While the purple toes syndrome is reported to be reversible, some cases progress to gangrene or necrosis which may require debridement of the affected area, or may lead to amputation.Heparin-induced thrombocytopeniaWarfarin sodium should be used with caution in patients with heparin-induced thrombocytopenia and deep venous thrombosis.

Cases of venous limb ischemia, necrosis, and gangrene have occurred in patients with heparin-induced thrombocytopenia and deep venous thrombosis 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 death6.A severe elevation (>50 seconds) in activated partial thromboplastin time (aPTT) with a PT/INR in the desired range as been identified as an indication of increased risk of postoperative hemorrhage.The decision to administer anticoagulants in the following conditions must be based upon clinical judgment in which the risks of anticoagulant therapy are weighed against the benefits:Lactation: Based on very limited published data, warfarin has not been detected in the breast milk of mothers treated with warfarin.

The same limited published data reports that some breast-fed infants, whose mothers were treated with warfarin, had prolonged prothrombin times, although not as prolonged as those of the mothers.

The decision to breastfeed should be undertaken only after careful consideration of the available alternatives.Women who are breastfeeding and anticoagulated with warfarin should be very carefully monitored so that recommended PT/INR values are not exceeded.

It is prudent to perform coagulation tests and to evaluate Vitamin K status in infants at risk for bleeding tendencies before advising women taking warfarin to breast-feed.

Effects in premature infants have not been evaluated.Severe to moderate hepatic or renal insufficiency.Infectious diseases or disturbances of intestinal flora: sprue, antibiotic therapy.Trauma which may result in internal bleeding.Surgery or trauma resulting in large exposed raw surfaces.Indwelling catheters.Severe to moderate hypertension.Known or suspected deficiency in protein C mediated anticoagulant response: Hereditary or acquired deficiencies of protein C or its cofactor, protein S, have been associated with tissue necrosis following warfarin administration.

Not all patients with these conditions develop necrosis, and tissue necrosis occurs in patients without these deficiencies.

Inherited resistance to activated protein C has been described in many patients with venous thromboembolic disorders but has not yet been evaluated as a risk factor for tissue necrosis.

The risk associated with these conditions, both for recurrent thrombosis and for adverse reactions, is difficult to evaluate since it does not appear to be the same for everyone.

Decisions about testing and therapy must be made on an individual basis.

It has been reported that concomitant anticoagulation therapy with heparin for 5 to 7 days during initiation of therapy with warfarin sodium may minimize the incidence of tissue necrosis.

Warfarin therapy should be discontinued when warfarin is suspected to be the cause of developing necrosis and heparin therapy may be considered for anticoagulation.Miscellaneous: polycythemia vera, vasculitis, and severe diabetes.Minor and severe allergic/hypersensitivity reactions and anaphylactic reactions have been reported.In patients with acquired or inherited warfarin resistance, decreased therapeutic responses to warfarin sodium have been reported.

Exaggerated therapeutic responses have been reported in other patients.Patients with congestive heart failure may exhibit greater than expected PT/INR response to warfarin sodium, thereby requiring more frequent laboratory monitoring, and reduced doses of warfarin sodium.Concomitant use of anticoagulants with streptokinase or urokinase is not recommended and may be hazardous.

Please note recommendations accompanying these preparations.)
Branded Drugs
The following US Branded drugs contain Warfarin Sodium


COUMADIN -- BRISTOL MYERS SQUIBB PHARMA CO

ATHROMBIN -- PHARMACEUTICAL RESEARCH ASSOC INC

JANTOVEN -- USL PHARMA INC

PANWARFIN -- ABBOTT LABORATORIES PHARMACEUTICAL PRODUCTS DIV


This web-site is for informational purposes only and is not intended as a substitute for advice from your doctor. It should not to be used for self-diagnosis or treatment.