Warfarin medication belong to Anticoagulants class. Warfarin interferes with hepatic synthesis of vitamin K-dependent clotting factors, resulting in in-vivo depletion of clotting factors II, VII, IX, and X. The elimination of warfarin is almost entirely by metabolism. It is metabolized by cytochrome P450 to inactive hydroxylated metabolites (predominant route) and by reductases to reduced metabolites (warfarin alcohols).

Warfarin is used for the prevention of recurrent transient ischemic attacks and reduction of risk of recurrent MI; adjunctive treatment of small cell carcinoma of lung.

How to Take Warfarin

Take Warfarin exactly as prescribed by health care provider. Warfarin is generally available in market in the form Tabletsas well as in powder and injection form.

Dosage Instructions for Warfarin Drug

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.

Contraindications of Warfarin Drug

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.

Interactions of Warfarin with other drugs

Aminoglutethimide, azathioprine, barbiturates, carbamazepine, cholestyramine, ethchlorvynol, ginseng, glutethimide, griseofulvin, mercaptopurine, rifabutin, rifampin, St. John's wort, trazodone, ubiquinone, and vitamin K: Decreased anticoagulant effect of warfarin.

Androgens, amiodarone, cefamandole, cefazolin, cefoperazone, cefotetan, cefoxitin, ceftriaxone, chloramphenicol, cimetidine, clofibrate, danshen, dextrothyroxine, disulfiram, dong quai, erythromycin, fluconazole, glucagon, methimazole, metronidazole, miconazole, moxalactam, nalidixic acid, NSAIDs, 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.

What are the Side Effects of Warfarin -

Like other medicines, Warfarin can cause side effects. Some of the more common side effects of Warfarin include

* Skin necrosis; gangrene; exfoliative dermatitis; urticaria; alopecia

* Nausea; vomiting; diarrhea; paralytic ileus; intestinal obstruction; anorexia; abdominal cramps

* Red-orange urine

* Hemorrhage; leukopenia

* Hepatotoxicity; cholestatic jaundice

* Fever; cholesterol microembolization (purple toe syndrome); hypersensitivity

Warnings and precautions before taking Warfarin :

* Caution patient before taking Warfarin 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 before taking Warfarin not to change brands of medicine.

* Advise patient before taking Warfarin to limit intake of vitamin K-rich foods, including avocados, bananas, broccoli, dried fruits, grapefruit, lima beans, nuts, oranges, peaches, potatoes, sunflower seeds, spinach, and tomatoes.

* Instruct patient to report any GI upset, pink or red discoloration of urine, red or tar-black stools or diarrhea, 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, night lights, and avoidance of activities that could result in bruising or bleeding.

* Tell patient before taking Warfarin not to take any OTC or prescription medications without consulting health care provider.

* Remind patient to wear Medi-Alert identification bracelet.

* Advise patient before taking Warfarin that follow-up visits will be required to monitor therapy and to keep appointments.

What if Overdose of Warfarin ?

If you think you or anyone else taken overdose of Warfarin , immediately telephone your doctor or contact your local or regional Poisons Information Centre Seek medical attention immediately. You may need urgent medical attention. Hematuria, excessive menstrual bleeding, melena, petechiae, oozing from superficial injuries are may be the overdose symptoms of Warfarin .

What if Missed Dose of Warfarin ?

If you miss a dose of Warfarin medicine and you remember within an hour or so, take the dose immediately. If you do not remember until later, skip the dose you missed and go back to your regular schedule. Do not double doses.

Storage Conditions for Warfarin :

* Do not give large loading dose.

* Do not switch brands.

* Administer at same time each day.

* Store Warfarin at room temperature in tight, light-resistant container.

* For IV use, give a slow bolus injection over 1 to 2 min in a peripheral vein.

* Reconstitute IV vial with 2.7 mL of Sterile Water for Injection.

* After reconstitution, solution is stable for 4 hr at room temperature.

* Check solution of Warfarin for particle matter or discoloration immediately before use. If either is present, do not use.

* Discard Warfarin unused solution.