GENERIC NAME: Warfarin

COMMON BRANDS: Coumadin, Jantoven

Warfarin is an oral prescription drug belongs to a class of medications known as anticoagulants (blood thinner). It works by decreasing the blood clotting by blocking the blood clotting factors (vitamin K epoxide reductase enzyme without this enzyme clotting factors II, VII, IX, and X have reduced clotting ability), which are needed to make clots. Warfarin is available only as an oral tablet with brand name version and the generic name version. The generic drug usually cost less.

What is Warfarin used for?

This drug is used to treat blood clots and helps to reduce the chance of developing blood clots in your body. Blood clots can cause heart attack, a stroke, or other dangerous conditions if they develop in your legs or lungs.

-Warfarin is used for the prevention or treatment of deep vein thrombosis and pulmonary embolism.
-Warfarin is used to decrease the risk of death, recurrent myocardial infarction (heart attack), and stroke.
-Warfarin is used for the prevention or treatment of thromboembolic complications associated with atrial fibrillation or heart valve replacement and certain surgeries (such as hip/knee replacement).

How to use Warfarin?

Before you start your treatment with warfarin, and each time you get a refill, read the patient information guideline if available from your pharmacist.

Take this drug as prescribed, do not alter your dose or take it more frequently than prescribed unless you discuss with your doctor.

Take this drug orally once per day, usually in the evening. To avoid confusion or missing of dose take this drug at the same time each day, before, during or after food.

Your doctor will monitor you by regular blood tests to ensure that your dose is correct.

It is required to maintain a balanced diet while taking warfarin. Some foods may hinder how warfarin works in your body and ultimately affect your treatment and dose.

It is essential to maintain a record of your daily doses as warfarin tablet comes in different strengths, each color represent different strength. Your prescriber may give you more than one tablet strength to make up your treatment.

Stick to the same brand of warfarin which is prescribed to you as these medicines are not interchangeable. Carefully check the brand and tablet strength on the medicine label to make sure that you are taking the right brand and strength as prescribed by your doctor.

What are the side effects of taking Warfarin?

The most common side effect associated with warfarin is bleeding, as it slows down the clotting time. In initial weeks of treatment, you are at high risk for bleeding with warfarin and also when you are unwell.

Get emergency medical assistance right away if you notice any signs of severe bleeding, such as easy bruising, prolonged bleeding from gums or cuts, unusual pain/swelling/discomfort, persistent/frequent nosebleeds, unusually heavy/ extended menstrual flow, coughing up blood, vomit that is bloody or looks like coffee grounds, pink/dark urine, severe headache, dizziness/fainting, persistent weakness, bloody/black/tarry stools, chest pain, shortness of breath, difficulty swallowing.

The other symptoms apart from bleeding are nausea, loss of appetite or abdominal pain, yellowing eyes/skin may occur. If any of these effects remain or get worse, tell your doctor promptly.

Even after you stop taking warfarin, this risk of bleeding can continue for up to a week.

Warfarin rarely can cause a severe issue (may be fatal) if it leads to a small blood clot which ultimately leads to the death of skin tissue (necrosis) that may require surgery or amputation if left untreated. This complication occurs most often at the beginning of treatment. If you notice any sores, changes in skin color temperature, or severe pain on your skin, seek immediate medical care.

Allergic reaction to this medicine is very rare. However, get medical help promptly if you notice any symptoms of a severe allergic reaction, itching/swelling (face/tongue/throat), such as rash, breathlessness. Hair loss is also observed with the use of this drug.

This is not a full record of all possible side effects. If you mark other effects not listed above, contact your doctor or pharmacist.

What are the precautions while using Warfarin?

Before using this drug, inform your doctor or pharmacist if you are allergic to it or if you have any other allergies.

Inform to all your doctors that you take warfarin before you have any medical or dental procedures. Discuss with your doctor this information even before minor procedures, like vaccinations and routine dental cleanings. If you are undergoing any surgery, you may need to reduce or discontinue your warfarin dose at least five days before the procedure. Your doctor may prescribe a shorter acting blood thinner(heparin).

Before using this medication, Discuss with your doctor about your medical history, mainly of blood disorders (like anemia, hemophilia), bleeding problems (like bleeding of the stomach/intestines), blood vessel disorders (such as aneurysms), recent major surgery, kidney disease, liver disease, alcohol use, mental/mood disorders (including memory problems), frequent falls/injuries.

Warfarin may cause stomach bleeding. Avoid regular use of alcohol along with this drug as it may further increase your risk for stomach bleeding and also affect how this medication works.

This medication can cause heavy bleeding. It is better to lower the chance of getting cut, injured, or bruised, use great caution with sharp objects like nail cutters and safety razors.

What are the drug interactions of Warfarin?

Warfarin may interact with other medications, herbs, or vitamins you may be using. A drug interaction is when a substance changes the way a drug works which can be harmful or hinder the drug from working well.

Do not start, stop, or alter the dose of the drug without discussing your doctor because your doctor may be monitoring you for possible drug interactions.

Your risk of bleeding is higher if you take warfarin with antiplatelet drugs such as aspirin (including all salicylates) and nonsteroidal anti-inflammatory drugs (NSAIDs such as ibuprofen, naproxen, celecoxib) which may have similar effects like warfarin. Talk to your doctor about using any medication (like acetaminophen) to treat fever/mild pain and ointments for pain-relieving (these products may contain NSAIDs or salicylates). Low-dose aspirin and related drugs (like ticlopidine, clopidogrel) should be continued if given by your doctor for a specific medical condition such as heart attack or stroke prevention.

Your risk of bleeding is higher if you take warfarin along with anticoagulants such as apixaban, edoxaban, rivaroxaban (factor Xa inhibitors) and dabigatran (direct thrombin inhibitors).

Your risk of bleeding is higher when you take warfarin along with SSRIs (selective serotonin reuptake inhibitors) and serotonin and norepinephrine reuptake inhibitors (SNRIs) citalopram, escitalopram, fluoxetine, paroxetine, duloxetine, venlafaxine and others.

This medication may intervene with specific lab test to measure theophylline levels, resulting in a false test. Assure that all your doctors and lab personnel know you use this drug.

WARNINGS:

Warfarin can cause severe bleeding that can be life-threatening and even cause death. Talk to your doctor if you have or ever had a blood or bleeding disorder, a history of stroke or heart attack, gastrointestinal bleeding, anaemia, diabetes, or kidney problems.

Do not take this medication if you are pregnant unless you have a mechanical heart valve. Warfarin may cause congenital disabilities, miscarriage, or death of a fetus if taken during the first trimester.

Warfarin can cause calciphylaxis. It is a rare but severe condition in which calcium is buildup in small blood vessels of fat and skin. People with kidney problem are at greater risk for this condition.

What are the forms and strengths of Warfarin?

Generic: Warfarin
Form: Oral tablet
Strengths: 1mg, 2mg, 2.5mg, 3mg, 4mg, 5mg, 6mg, 7.5mg, and 10mg

Brand: Coumadin
Form: Oral tablet
Strengths: 1mg, 2mg, 2.5mg, 3mg, 4mg, 5mg, 6mg, 7.5mg, and 10mg

Brand: Jantoven
Form: Oral tablet
Strengths: 1mg, 2mg, 2.5mg, 3mg, 4mg, 5mg, 6mg, 7.5mg, and 10mg

What is the dosage of Warfarin?

For Reducing the Risk of Death, another Heart Attack, or Stroke:

Adult (18 and above):

The dose of warfarin is based on your prothrombin time (PT)/international normalised ratio (INR) blood test. The typical initial dose is 5mg to 10mg once per day. Your dose may change if needed based on your test and condition.

Pediatric:

Children (0 to 17 years):

Safety and efficacy of the drug have not been established for this age group.

For Prophylaxis and Treatment of Clots with Atrial Fibrillation or Heart Valve Replacement:

Adult (18 and above):

The dose of warfarin sodium is based on your prothrombin time (PT)/international normalised ratio (INR) blood test. The initial dose is 5mg to 10mg once per day. Your dose may change if needed based on your test and condition.

Children (0 to 17 years):

Safety and efficacy of the drug have not been established for this age group.

For Prophylaxis and Treatment of Clots in the Lower Body and the Lungs:

Adult (18 and above):

The dose of warfarin sodium is based on your prothrombin time (PT)/international normalised ratio (INR) blood test. The initial dose is 5mg to 10mg once per day. Your dose may change if needed based on your test and condition.

Children (0 to 17 years):

Safety and efficacy of the drug have not been established for this age group.

Special Considerations:

For older adults above 60 years of age are more sensitive to warfarin. Your doctor may initiate your treatment with a low dose of warfarin if needed gradually increase your dose.

Consider the dose of the drug based on genotype (see Genomic Considerations).

Most common questions asked about Warfarin / Q&A’s:

Can Warfarin damage the kidneys?

According to the research conducted by the “University of Alabama” at Birmingham, Alabama on 578 patients using warfarin. An estimated 60 % of the patients had normal or mildly reduced kidney function. Another 30 % had moderately reduced kidney function, more common in older adults. The remaining 10 %,  had kidney failure and required dialysis. Warfarin dose was significantly affected by kidney function.

Disclaimer

TheMedPharma has made every effort to make sure that all the information is factually correct, comprehensive, and up-to-date. However, this website should not be considered as a substitute for the advice, knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or licensed health care professional before taking any medication. The drug information contained herein is subjected to changes if required. The lack of warnings or other information for a given drug does not mean that the drug or its combination is safe, effective or appropriate for use in all patients.