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Warfarin sodiumGeneric Name :warfarin sodium

Brand Name: Apo-Warfarin (CAN), Coumadin, Gen-Warfarin (CAN)

Classification:Oral anticoagulant, Coumarin derivative

Pregnancy Category X

Dosage & Route

Available forms :Tablets1, 2, 2.5, 3, 4, 5, 6, 7.5, 10 mg; powder for injection5.4 mg

reconstitutes to 2 mg/mL

Dosages :Adjust dosage according to the one-stage PT to achieve and maintain 1.52.5

times the control value or prothrombin activity 20%30% of normal; PT ratio of 1.31.5 or

INR of 23. IV use is reserved for situations in which oral warfarin is not feasible. Dosages

are the same for oral and IV forms.

ADULTS

Initially, 25 mg/day PO. Adjust dose according to PT response. For maintenance, 210 mg/day PO based on PT ratio or INR.

GERIATRIC PATIENTS

Lower doses are usually needed; begin with smaller doses than those recommendedfor adults and closely monitor PT ratio or INR.

Therapeutic actions

Warfarin inhibits synthesis of vit K-dependent coagulation factors VII, IX, X and IIand anticoagulant protein C and its cofactor protein S. No effects on establishedthrombus but further extension of the clot can be prevented. Secondary embolicphenomena are avoided.

Indications

Venous thrombosis and its extension, treatment, and prophylaxis Treatment of thromboembolic complications of atrial fibrillation with embolization,

and cardiac valve replacement

Pulmonary embolism, treatment, and prophylaxis

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Prophylaxis of systemic embolization after acute MI Unlabeled uses:Prevention of recurrent TIAs, prevention of recurrent MI, adjunct to

therapy in small-cell carcinoma of the lung

Adverse effects

Hypersensitivity, rash, alopecia, diarrhea, drop in hematocrit, purple toes syndrome,skin necrosis, jaundice, nausea, vomiting, hepatic dysfunction, pancreatitis,

increased LFT. Potentially Fatal:Hemorrhage.

Contraindications

Hypersensitivity; hemorrhagic tendencies or blood dyscrasia; recent surgery; pepticulcer; severe hypertension; bacterial endocarditis; cerebrovascular disorders;

psychosis; senility; aneurysms; pericarditis; pericardial effusion; eclampsia; pre-eclampsia; threatened abortion; alcoholism; severe renal and hepatic impairment;pregnancy.

Nursing considerations

Assessment

History:Allergy to warfarin; SBE; hemorrhagic disorders; TB; hepatic diseases; GIulcers; renal disease; indwelling catheters, spinal puncture; aneurysm; diabetes;visceral carcinoma; uncontrolled hypertension; severe trauma; threatened abortion,menometrorrhagia; pregnancy; lactation; CHF, diarrhea, fever; thyrotoxicosis;

senile, psychotic or depressed patients

Physical:Skin lesions, color, T; orientation, reflexes, affect; P, BP, peripheralperfusion, baseline ECG; R, adventitious sounds; liver evaluation, bowel sounds,normal output; CBC, urinalysis, guaiac stools, PT, LFTs, renal function tests

Interventions

Do not use drug if patient is pregnant (heparin is anticoagulant of choice); advisepatient to use contraceptives.

Monitor PT ratio or INR regularly to adjust dosage. Administer IV form to patients stabilized on Coumadin who are not able to take oral

drug. Dosages are the same. Return to oral form as soon as feasible.

Do not change brand names once stabilized; bioavailability may be a problem. WARNING: Evaluate patient regularly for signs of blood loss (petechiae, bleeding

gums, bruises, dark stools, dark urine). Maintain PT ratio of 1.31.5, 1.52 with

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mechanical prosthetic valves or recurrent systemic embolism; INR ratio of 23, 3

4.5 with mechanical prosthetic valves or recurrent systemic emboli.

Do not give patient any IM injections. WARNING: Double check all drugs ordered for potential drug interactions; dosage of

both drugs may need to be adjusted. Use caution when discontinuing other drugs; warfarin dosage may need to be

adjusted; carefully monitor PT values. Keep vitamin K readily available in case of overdose. Arrange for frequent follow-up, including blood tests to evaluate drug effects. WARNING: Evaluate for therapeutic effects: INR within therapeutic range.

Teaching points

Many factors may change your body's response to this drugfever, change of diet,change of environment, other medications. Your dosage may have to be changedrepeatedly. Write down changes that are prescribed.

Do not start or stop taking any medication without consulting your health careprovider. Other drugs can affect your anticoagulant; starting or stopping anotherdrug can cause excessive bleeding or interfere with the desired drug effects.

Carry or wear a medical ID tag to alert emergency medical personnel that you aretaking this drug.

Avoid situations in which you could be easily injured (contact sports, shaving with astraight razor).

Have periodic blood tests to check on the drug action. These tests are important. Use contraception; do not become pregnant while taking this drug. You may experience these side effects: Stomach bloating, cramps (transient); loss of

hair, rash; orange-red discoloration to the urine (if upsetting, add vinegar to your

urine and the color should disappear).

Report unusual bleeding (from brushing your teeth, excessive bleeding from injuries,excessive bruising), black or bloody stools, cloudy or dark urine, sore throat, fever,

chills, severe headaches, dizziness, suspected pregnancy.