Warfarin (Coumadin)

Pregnancy Category

Category X; Category D for patient with mechanical heart valve. Risk outweighs benefits. Should not be taken.

Administration

- Give drug at same time daily. - Establish baseline coagulation parameters before therapy. - PT and INR determinations are essential for proper control. Recommended INR range is usually 2 to 3 for most patients.

Indications

- It is used to treat blood clots. - It is used to thin the blood so that clots will not form. - It is used to lower the chance of heart attack, stroke, and death in some people. - PE, DVT, MI, rheumatic heart disease with heart valve damage, prosthetic heart valves, chronic atrial fibrillation

Nursing Considerations

- Obtain daily INR determinations upon initiation until stable in the therapeutic range; then, every 1 to 4 weeks. - Avoid IM injections when possible. - Regularly inspect patient for bleeding gums, bruises on arms or legs, petechiae, nosebleeds, melena, tarry stools, hematuria, and hematemesis. - Monitor patient for purple-toes syndrome. - Withhold drug and call prescriber at once in the event of fever or rash (signs of severe adverse reactions). - Make sure that patient isn't taking additional anticoagulants unless instructed by prescriber.

Patient Teaching

- Stress importance of complying with prescribed dosage and follow-up appointments. Tell patient to carry a card that identifies patient's increased risk of bleeding. - Tell patient and family about measures to prevent bleeding, to watch for signs of bleeding or abnormal bruising, and to call prescriber at once if they occur. - Avoid OTC products containing aspirin, other salicylates, or drugs that may interact with warfarin unless ordered by prescriber. - Consult prescriber before initiating any herbal therapy as many herbs have anticoagulant, antiplatelet, or fibrinolytic properties. - Consult prescriber before using miconazole vaginal cream or suppositories. Abnormal bleeding and bruising have occurred. - Instruct female patient to notify prescriber if menstruation is heavier than usual; she may need dosage adjustment. - Tell patient to read food labels. Food, nutritional supplements, and multivitamins that contain vitamin K may impair anticoagulation.

Black Box Warnings

- Warfarin can cause major or fatal bleeding, which is more likely to occur during the starting period and with a higher dose. Regularly monitor INR in all patients. Consider more frequent INR monitoring in those at high risk for bleeding. - Drugs, dietary changes, and other factors affect INR levels achieved with warfarin therapy.

An INR range of _________________ is generally an effective therapeutic range for people taking warfarin for disorders such as atrial fibrillation or a blood clot in the leg or lung.

2.0 to 3.0

Therapeutic classification

Anticoagulants

Adverse Reactions

CV: vasculitis. GI: abdominal pain, diarrhea, flatulence, bloating, nausea, taste perversion, vomiting. Hematologic: hemorrhage. Hepatic: hepatitis. Respiratory: tracheal or tracheobronchial calcification. Skin: alopecia, pruritus, rash, dermatitis, bullous eruptions. Other: chills, hypersensitivity or allergic reactions, including anaphylactic reactions and urticaria.

Pharmacologic classification

Coumarin derivatives

Drug-Food Interations

Cranberry juice: May increase risk of severe bleeding. Discourage use together.

A ______________ test is used to check whether medicine to prevent blood clots is working.

PT INR

Available Forms

Tablets: 1 mg; 2 mg; 2.5 mg; 3 mg; 4 mg; 5 mg; 6 mg; 7.5 mg; 10 mg