Warfilone

A to Z Drug Facts

Warfilone

	Action
	Indications
	Contraindications
	Route/Dosage
	Interactions
	Lab Test Interferences
	Adverse Reactions
	Precautions
Patient Care Considerations
	Administration/Storage
	Assessment/Interventions
	Patient/Family Education

(WORE-fuh-rin)

Coumadin, Warfilone

Class: Anticoagulant

Action Interferes with hepatic synthesis of vitamin K-dependent clotting factors, resulting in in-vivo depletion of clotting factors II, VII, IX, and X.

Indications Prophylaxis and treatment of venous thrombosis and its extension; prophylaxis and treatment of atrial fibrillation with embolization; prophylaxis and treatment of pulmonary embolism; adjunct in prophylaxis of systemic embolism after MI. Unlabeled use(s): Prevention of recurrent transient ischemic attacks and reduction of risk of recurrent MI; adjunctive treatment of small cell carcinoma of lung.

Contraindications Pregnancy; hemorrhagic tendencies; hemophilia; thrombocytopenic purpura; leukemia; recent or contemplated surgery of eye or CNS, major regional lumbar block anesthesia, or surgery resulting in large, open surfaces; patients bleeding from GI, respiratory or GU tract; threatened abortion; aneurysm; ascorbic acid deficiency; history of bleeding diathesis; prostatectomy; continuous tube drainage of small intestine; polyarthritis; diverticulitis; emaciation; malnutrition; cerebrovascular hemorrhage; eclampsia and preeclampsia; blood dyscrasias; severe uncontrolled or malignant hypertension; severe renal or hepatic disease; pericarditis and pericardial effusion; subacute bacterial endocarditis; visceral carcinoma; following spinal puncture and other diagnostic or therapeutic procedures (eg, IUD insertion) with potential for uncontrollable bleeding; history of warfarin-induced necrosis.

Route/Dosage

ADULTS: PO 2 to 5 mg/day initially for 2 to 4 days; adjust daily dose according to prothrombin time (PT) or international normalization ratio (INR) determinations. Usual maintenance dose is PO 2 to 10 mg daily. ELDERLY PATIENTS:Lower dosages are recommended. ADULTS: IV Provides an alternative administration route for patients who cannot receive oral drugs. The IV dosages would be the same as those that would be used orally. Administer as a slow bolus injection over 1 to 2 minutes in a peripheral vein.

Interactions

Aminoglutethimide, azathioprine, barbiturates, carbamazepine, cholestyramine, ethchlorvynol, glutethimide, griseofulvin, mercaptopurine, rifabutin, rifampin, trazodone, and vitamin K: Decreased anticoagulant effect of warfarin. Androgens, amiodarone, cefamandole, cefazolin, cefoperazone, cefotetan, cefoxitin, ceftriaxone, chloramphenicol, cimetidine, clofibrate, dextrothyroxine, disulfiram, erythromycin, fluconazole, glucagon, methimazole, metronidazole, miconazole, moxalactam, nalidixic acid, nonsteroidal anti-inflammatory agents, phenylbutazone, propylthiouracil, quinidine, quinine, salicylates, sulfinpyrazone, sulfonamides, thyroid hormones, tricyclic antidepressants, and vitamin E: Increased anticoagulant effect of warfarin. Hydantoins: Serum hydantoin concentration may be elevated, increasing risk of toxicity.

Lab Test Interferences Oral anticoagulants may cause red-orange discoloration of alkaline urine, interfering with some laboratory tests.

Adverse Reactions

DERM: Skin necrosis; gangrene; exfoliative dermatitis; urticaria; alopecia. EENT: Mouth ulcers. GI: Nausea; vomiting; diarrhea; paralytic ileus; intestinal obstruction; anorexia; abdominal cramps. HEMA: Hemorrhage; leukopenia. Hepatotoxicity; cholestatic jaundice. GU: Red-orange urine. OTHER: Fever; cholesterol microembolization (purple toe syndrome); hypersensitivity.

Precautions

Pregnancy: Category X. Lactation: Excreted in breast milk. Children: Safety and efficacy not established in children < 18 yr. Elderly patients: May be more sensitive to effects. Special risk patients: There is increased risk associated with using warfarin in patients with trauma, infection, renal insufficiency, dietary insufficiency, uncontrolled hypertension, polycythemia vera, vasculitis, indwelling catheters. Evaluate benefits of therapy vs. risks. Adrenal hemorrhage: Discontinue therapy if patient develops signs and symptoms of adrenal insufficiency. Hemorrhage/Necrosis: Most serious risks of therapy; may result in death. Hepatic impairment: Use cautiously. Hypersensitivity: Reactions range from mild to life-threatening. Symptoms may be dermatologic (eg, erythema, eczematous rash, exfoliative dermatitis, exudative erythema multiforme, alopecia), hematologic (eg, eosinophilia, leukopenia, thrombocytopenia), renal, (eg, nephropathy, nephritis, oliguria), GI (eg, enanthema, severe stomatitis), or hepatic (eg, mixed hepatocellular damage, cholestasis, jaundice). If signs or symptoms occur, discontinue therapy and notify health care provider. Monitoring/Prothrombin time: Individualize treatment based on PT or INR. Protein C deficiency: Hereditary, familial, or clinical protein C deficiency has been associated with necrosis following warfarin therapy. If warfarin is suspected cause of necrosis, discontinue administration. Purple toe syndrome: Systemic cholesterol microembolization from release of atheromatous plaque emboli. Discontinue therapy. Surgical/dental procedures: Adjust dose to maintain PT or INR at low end of therapeutic range for patients who must be anticoagulated during dental or surgical procedures.

PATIENT CARE CONSIDERATIONS

Administration/Storage

Do not give large loading dose.
Do not switch brands.
Administer at same time each day.
Store at room temperature in tight, light-resistant container.
For IV use, give a slow bolus injection over 1 to 2 minutes in a peripheral vein.
Reconstitute IV vial with 2.7 ml of Sterile Water for Injection.
After reconstitution, solution is stable for 4 hours at room temperature.
Check solution for particle matter and/or discoloration immediately before use. If either is present, do not use.
Discard unused solution.

Assessment/Interventions

Obtain patient history, including drug history and any known allergies.
Use care in determining cooperation of patient to ensure compliance.
Monitor PT or INR.
Test urine, stool, and drainage for occult blood.
Observe for low back pain and GI symptoms.
Avoid IM injection and venipuncture if possible.
If “purple toe syndrome,” tissue necrosis or signs of adrenal insufficiency (fever, myalgia, arthralgia, anorexia, nausea, diarrhea) are observed, stop drug and report to health care provider immediately.
If bleeding occurs, report to health care provider immediately.

OVERDOSAGE: SIGNS & SYMPTOMS
	Hematuria, excessive menstrual bleeding, melena, petechiae, oozing from superficial injuries

Patient/Family Education

Caution patient that this medication must not be taken during pregnancy or when pregnancy is possible. Advise patient to use reliable form of birth control while taking this drug.
Advise patient not to change dose unless advised by health care provider.
Advise patient not to drastically change diet or consume alcohol.
Advise patient not to change brands of medicine.
Advise patient to limit intake of vitamin K-rich foods, including avocados, bananas, broccoli, dried fruits, grapefruit, lima beans, nuts, oranges, peaches, potatoes, sunflower seeds, spinach, tomatoes.
Instruct patient to report any GI upset, pink or red discoloration of urine, red or tar-black stools or diarrhea, skin rash, yellowish tint of skin or eyes, unusual bleeding (eg, heavier than normal menstrual flow), or bruising.
Caution patient not to take aspirin or other salicylates without consulting health care provider.
Instruct patient in safety practices: Use of soft toothbrush, electric razor, nightlights and avoidance of activities that could result in bruising or bleeding.
Tell patient not to take any otc or prescription medications without consulting health care provider.
Remind patient to wear Medi-Alert identification bracelet.