"Sept. 8, 2011 -- An FDA advisory panel has voted to recommend approval of a new blood thinner to prevent strokes and dangerous blood clots in patients with the heart rhythm disorder atrial fibrillation.
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Suspected or overt abnormal bleeding (e.g., appearance of blood in stools or urine, hematuria, excessive menstrual bleeding, melena, petechiae, excessive bruising or persistent oozing from superficial injuries) are early manifestations of anticoagulation beyond a safe and satisfactory level.
Excessive anticoagulation, with or without bleeding, may be controlled by discontinuing Jantoven® Tablets (Warfarin Sodium Tablets, USP) therapy and if necessary, by administration of oral or parenteral vitamin K1 . (Please see recommendations accompanying vitamin K1 preparations prior to use.)8,9
Such use of vitamin K1 reduces response to subsequent Jantoven (warfarin sodium tablets) ® Tablets therapy. Patients may return to a pretreatment 1 thrombotic status following the rapid reversal of a prolonged PT/INR. Resumption of Jantoven® Tablets (warfarin sodium tablets) administration reverses the effect of vitamin K, and a therapeutic PT/INR can again be obtained by careful dosage adjustment. If rapid anticoagulation is indicated, heparin may be preferable for initial therapy.
If minor bleeding progresses to major bleeding, give 5 to 25 mg (rarely up to 50 mg) parenteral vitamin K1 . In emergencysituations of severe hemorrhage, clotting factors can be returned to normal by administering 200 to 500 mL of fresh whole blood or fresh frozen plasma, or by giving commercial Factor IX complex.
A risk of hepatitis and other viral diseases is associated with the use of these blood products; Factor IX complex is also associated with an increased risk of thrombosis. Therefore, these preparations should be used only in exceptional or life-threatening bleeding episodes secondary to Jantoven® Tablets (warfarin sodium tablets) overdosage.
Purified Factor IX preparations should not be used because they cannot increase the levels of prothrombin, Factor VII and Factor X which are also depressed along with the levels of Factor IX as a result of Jantoven® Tablets (warfarin sodium tablets) treatment. Packed red blood cells may also be given if significant blood loss has occurred. Infusions of blood or plasma should be monitored carefully to avoid precipitating pulmonary edema in elderly patients or patients with heart disease.
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:
Jantoven® Tablets (Warfarin Sodium Tablets, USP) 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.
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.
Inadequate laboratory facilities.
Spinal puncture and other diagnostic or therapeutic procedures with potential for uncontrollable bleeding.
8. Salem DN, Stein PD, Al-Ahmad A, et al. Antithrombotic therapy in valvular heart disease-native and prosthetic. The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest. 2004;126:457S-482S.
9. American Geriatrics Society Clinical Practice Guidelines. The use of oral anticoagulants (warfarin) in older people. J Amer Geriatr Soc. 2000;48:224-227.
Last reviewed on RxList: 3/24/2008
This monograph has been modified to include the generic and brand name in many instances.
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