warfarin, Coumadin, Jantoven (cont.)
Omudhome Ogbru, PharmD
Omudhome Ogbru, PharmD
Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.
GENERIC AVAILABLE: Yes
PREPARATIONS: Tablets: 1, 2, 2.5, 3, 4, 5, 6, 5, 7.5 and 10 mg. Powder for Injection: 5 mg/vial
STORAGE: Warfarin should be stored at room temperature, 59 F to 86 F (15 C to 30 C), in tight, light resistant container.
PRESCRIBED FOR: Warfarin is used in treating patients with deep vein thrombosis (DVT) to prevent extension of the clot, and to reduce the risk of pulmonary embolism. Patients with pulmonary embolism are treated with warfarin to prevent further emboli. Warfarin also is used in patients with atrial fibrillation or artificial heart valves to reduce the risk of strokes, and after a heart attack. It also is helpful in preventing blood clots from forming in certain orthopedic surgeries such as knee or hip replacements. Warfarin is used in preventing closure of coronary artery stents due to clotting.
DOSING: Warfarin may be taken with or without food. Since warfarin is metabolized (inactivated) by the liver and then excreted by the kidneys, dosages need to be lowered in patients with liver and kidney dysfunction. Frequent blood tests (INR test) are performed to measure the effect of warfarin and to adjust dosing. There are published INR ranges for the various uses of warfarin. Treatment usually is started at 2 to 5 mg once daily and the dose is adjusted based in INR tests. Patients typically require 2 to 10 mg of warfarin daily.
DRUG INTERACTIONS: Many drugs, both prescription and nonprescription (OTC), can affect the anticoagulant action of warfarin or increase the risk of bleeding. Patients on warfarin should regularly consult their doctor before instituting any medications on their own. It also is advisable for patients on warfarin to carry identification such as bracelets to alert other health professionals to the presence of anticoagulation. Following are a few examples of drugs that interact with warfarin. Drugs the increase the effect of warfarin by reducing the breakdown of warfarin include amiodarone (Cordarone), trimethoprim/sulfamethoxazole (Bactrim), fluconazole (Diflucan), itraconazole (Sporanox), fluvastatin, fluvoxamine, metronidazole miconazole, voriconazole (Vfend), zafirlukast (Accolate), ciprofloxacin (Cipro), cimetidine, atorvastatin (Lipitor), clarithromycin (Biaxin), fluoxetine (Prozac), indinavir (Crixivan), and ritonavir (Norvir).
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