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DSI Newsletters, Issue 65:
Coumadin: A Patient's Guide

What is warfarin?
 Warfarin is an anticoagulant medicine that decreases the ability of blood to form clots. Coumadin is the brand name. Type of medicine: anticoagulant (blood thinner)
What is this medicine used for?
 This medicine is a blood thinner taken by mouth to prevent blood clots from forming in the blood vessels. It may be used to help treat irregular heartbeats and after a heart attack or heart valve replacement surgery.
 It may be used for other conditions as determined by your health care provider.
What should my health care provider know before I take this medicine?
 Before taking this medicine, tell your health care provider if you have ever had:
  1. an allergic reaction to any medicine
  2. a stroke
  3. bleeding problems
  4. cancer
  5. diabetes
  6. heart disease
  7. high blood pressure
  8. kidney or liver disease
  9. problems with alcohol abuse
  10. stomach ulcers
  11. thyroid problems.
Tell your provider if you have recently had surgery or any kind of infection.
 Females of childbearing age: Do not take this medicine if you are pregnant or plan to become pregnant. If you become pregnant while you are taking this medicine, stop taking it and contact your health care provider right away. Do not breast-feed while taking this medicine without your health care provider's approval.
How does it work?
 Blood clots may form in people who have artificial valves, irregular heartbeats (atrial fibrillation), or clotting disorders. Blood clots that form when they shouldn't can be dangerous. They can cause problems, including:
  1. stroke, which blocks blood flow to the brain
  2. blockage of veins or arteries in the legs or in organs such as the lungs and kidneys.
When is it used?
 Warfarin is used to prevent blood clots in the legs from coming back, and to treat heart attacks and certain kinds of stroke caused by a kind of irregular heartbeat called atrial fibrillation.
How do I take it?
 Take this medicine exactly as your health care provider prescribes. Do not take less or the medicine may not be effective. Taking more may cause bleeding.
 Do not change brands of this medicine without talking to your health care provider or pharmacist. Other brands may affect you differently.
 If you miss a dose of this medicine, take it as soon as you remember on the same day. Do not take a double dose. If you miss a day's dose, contact your health care provider right away.
What should I watch out for?
 You will need to have blood tests regularly while you take this medicine. The main test is called prothrombin time, or PT and is now a days reported in INR units. Therapeutic is between 2.0 and 3.0. If too much Coumadin is given the INR goes greater than 3.0 and you are at risk of bleeding. If too little Coumadin is given the INR will be less than 2.0 and you will be at risk of clotting. Tests results are used to adjust the dose of warfarin. The medicine should keep the blood just thin enough to prevent clots (INR > 2.0). If the blood is too thin, you may bleed too easily (INR >3.0).
 While taking warfarin it is very important that you:
  1. Tell all healthcare providers, dentists, and pharmacists that you take warfarin. Carry some form of written notice or wear a bracelet that states you are taking warfarin.
  2. Do not take any other medicines, including nonprescription products, vitamins, or natural remedies unless your health care provider approves. Warfarin can interact with many other medicines including aspirin, pain relievers, and antibiotics. The interaction may cause bleeding or other serious side effects. Also, do not stop taking any medicines or change the amounts you take unless you talk to your health care provider or pharmacist first.
  3. Do not make big changes in your diet, such as eating a lot more green leafy vegetables than you usually eat. Vitamin K is found in leafy green vegetables, certain legumes, green tea, and vegetable oils. Eat a healthy balanced diet with about the same amount of vitamin K each day. Your diet affects the way warfarin thins your blood.
  4. If you miss a dose, take it as soon as you remember on the same day. Do not take a double dose of this medicine. Keep a record of the missed dose and report it to your health care provider or pharmacist at the next visit. Call your healthcare provider if you miss more than one dose.
  5. Do not drink a lot of alcohol. It may interfere with this medicine. Talk with your provider about this.
  6. Keep warfarin out of the reach of children and pets.
  7. Do not take warfarin if you are pregnant or plan to become pregnant.
 Bleeding is a possible side effect from this medicine. Call your health care provider right away if you have:
  1. a serious fall or hard bump to the head or any unusual bruising
  2. bleeding that does not stop, from a cut, from your nose, or from the vagina
  3. dark brown or reddish colored urine
  4. bloody, black, or tarry stools
  5. vomiting or coughing up blood
  6. fever, diarrhea, or infection
  7. pain or swelling in your feet or legs
  8. dizziness
  9. trouble breathing
  10. chest pain
  11. unusual weakness or tiredness.
 You will need to have blood and lab tests regularly to see how this medicine affects you. Keep all appointments for these tests.
 Many other medicines, even aspirin and vitamins, may affect the action of this medicine. Tell your health care provider and pharmacist about any other prescription or nonprescription medicines, vitamins, or natural remedies you are taking. Do not take any other medicines unless your health care provider approves. Also, do not stop taking any medicines without talking to your health care provider or pharmacist.
 Follow the diet and exercise program your health care provider recommends. While you are taking this medicine, eat a healthy balanced diet with about the same amount of vitamin K each day. Vitamin K is found in leafy green vegetables, certain legumes, green tea, and vegetable oils. Do not make big changes in your diet, such as eating a lot more green leafy vegetables than you usually eat. Your diet affects the way this medicine thins your blood.
 This medicine may cause you to bleed more easily or to bleed longer. Avoid sports and activities that may cause injuries. If you fall or are injured, contact your health care provider right away. Serious internal bleeding may occur without your knowing about it.
 If you need emergency care, surgery, lab tests, or dental work, tell the health care provider or dentist you are taking this medicine. Wear some form of identification stating that you take this medicine (such as a Medic Alert bracelet).
 Contact your health care provider to report any illness, such as diarrhea, infection, or fever. These problems may change the effect of this medicine.
 Drinking too much alcohol may interfere with this medicine. Talk to your health care provider about this.
 Adults over the age of 65 may be at greater risk for side effects. Talk to your health care provider about this.
What are the possible side effects?
 Along with its needed effects, your medicine may cause some unwanted side effects. Some side effects may be very serious. Some side effects may go away as your body adjusts to the medicine. Tell your health care provider if you have any side effects that continue or get worse.
 Serious (report these to your health care provider right away): Unusual bruising or bleeding; dark urine or stools; bloody urine; increased menstrual flow or vaginal bleeding; painful urination; discolored fingers or toes; mouth sores; swelling, numbness, or tingling in fingers or toes; sore throat; fever; sudden weight gain; yellowish eyes or skin; severe headache, dizziness, or weakness; diarrhea; rash; itching; stomach pain; severe joint or muscle pain; shortness of breath.
 Other (usually temporary): Bloating, gas, loss of appetite, hair loss.
What products might interact with this medicine?
 Do not take any other medicines, including nonprescription products, vitamins, or natural remedies unless your health care provider approves. When you take this medicine with other medicines, it can change the way this or any of the other medicines work. Nonprescription medicines, vitamins, natural remedies, and certain foods may also interact. Using these products together might cause harmful side effects, such as bleeding or other serious side effects. Talk to your health care provider if you are taking:
  1. analgesics (pain medicine) such as acetaminophen (Tylenol), ibuprofen (Motrin, Motrin IB, Advil, Nuprin), naproxen (Naprosyn, Anaprox, Aleve, Naprelan), ketoprofen (Orudis, Orudis KT, Oruvail), nabumetone (Relafen), indomethacin (Indocin), ketorolac (Toradol), mefenamic acid (Ponstel), sulindac (Clinoril), piroxicam (Feldene), diclofenac (Voltaren, Cataflam), oxaprozin (Daypro), tramadol (Ultram), propoxyphene (Darvocet N-100), and celecoxib (Celebrex)
  2. antiandrogen medicine such as danazol (Danocrine) and oxymetholone (Anadrol-50)
  3. antianxiety medicine such as chlordiazepoxide (Librium)
  4. antibiotics such as ciprofloxacin (Cipro), levofloxacin (Levaquin), ofloxacin (Floxin), azithromycin (Zithromax, Z-pak), clarithromycin (Biaxin), erythromycin (Ery-Tabs, E.E.S., Eryc), griseofulvin (Fulvicin, Grisactin, Gris-Peg), troleandomycin (Tao), norfloxacin (Noroxin) ), penicillin, ampicillin (Omnipen), dicloxacillin (Dycill), oxacillin (Bactocill), demeclocycline (Declomycin), doxycycline (Vibramycin, Vibra-Tabs, Doryx, Doxychel), nalidixic acid (NegGram), minocycline (Minocin, Vectrin), oxytetracycline (Terramycin), tetracycline (Achromycin V, Sumycin, Panmycin, Tetracyn), isoniazid (Nydrazid), sulfamethoxazole (Bactrim, Septra), sulfisoxazole (Gantrisin), piperacillin (Pipracil, Zosyn), neomycin, cefamandole (Mandol), cefoxitin (Mefoxin), cefazolin (Ancef, Kefzol), cefoperazone (Cefobid), cefotetan (Cefotan), ceftriaxone (Rocephin), chloramphenicol, rifampin (Rifadin, Rimactane), and ticarcillin (Ticar, Timentin)
  5. anticonvulsants such as carbamazepine (Tegretol), primidone (Mysoline), valproic acid (Depacon, Depakene, Depakote), and phenytoin (Dilantin)
  6. antifungal medicines such as fluconazole (Diflucan), metronidazole (Flagyl), miconazole (Monistat, Micatin), clotrimazole (Mycelex), itraconazole (Sporanox), and ketoconazole (Nizoral)
  7. antihistamines such as diphenhydramine (Benadryl) and chlorpheniramine (Chlor-Trimeton)
  8. anti-HIV medicines such as indinavir (Crixivan), saquinavir (Invirase, Fortovase), nelfinavir (Viracept), nevirapine (Viramune), amprenavir (Agenerase), and ritonavir (Norvir)
  9. antiplatelet medicines such as ticlopidine (Ticlid), dipyridamole (Persantine), and clopidogrel (Plavix)
  10. antipsychotic medicine such as haloperidol (Haldol) and clozapine (Clozaril)
  11. aspirin and other salicylates
  12. asthma medicine such as zileuton (Zyflo) and zafirlukast (Accolate)
  13. barbiturates such as phenobarbital, amobarbital (Amytal), butabarbital (Butisol), pentobarbital (Nembutal), and secobarbital (Seconal)
  14. birth control pills and hormones such as estradiol (Estrace, Estratab), conjugated estrogens (Premarin), norethindrone (Aygestin, Micronor), and norgestrel (Ovrette)
  15. blood pressure medicine such as timolol (Blocadren), nadolol (Corgard), propranolol (Inderal), acebutolol (Sectral), pindolol (Visken), atenolol (Tenormin), esmolol (Brevibloc), betaxolol (Kerlone), bisoprolol (Zebeta), metoprolol (Lopressor, Toprol XL), methyldopa (Aldomet), sotalol (Betapace), labetalol (Normodyne, Trandate), and carvedilol (Coreg)
  16. blood thinners such as enoxaparin (Lovenox), dalteparin (Fragmin), and heparin
  17. cholesterol-lowering medicines such as atorvastatin (Lipitor), fluvastatin (Lescol), lovastatin (Mevacor), pravastatin (Pravachol), simvastatin (Zocor), cholestyramine (Questran), clofibrate (Atromid-S), fenofibrate (TriCor), gemfibrozil (Lopid), and colestipol (Colestid)
  18. corticosteroids such as cortisone (Cortone), betamethasone (Celestone), dexamethasone (Decadron), fludrocortisone (Florinef), hydrocortisone (Cortef, Hydrocortone, A-HydroCort), methylprednisolone (Medrol), prednisone (Meticorten, Deltasone, Orasone), prednisolone (Delta-Cortef), and triamcinolone (Aristocort, Kenacort)
  19. diabetes medicines such as chlorpropamide (Diabinese), tolbutamide (Tol-tab).glyburide (DiaBeta, Micronase), glipizide (Glucotrol), repaglinide (Prandin), metformin (Glucophage), rosiglitazone (Avandia), and pioglitazone (Actos)
  20. disulfiram (Antabuse)
  21. diuretics (water pills) such as chlorthalidone and spironolactone (Aldactone)
  22. gout medicines such as allopurinol (Zyloprim, Aloprim)
  23. heart medicines such as propafenone (Rythmol), quinidine (Quinora, Quinidex, Quinaglute, Cardioquin), moricizine (Ethmozine), and amiodarone (Cordarone; Pacerone)
  24. heartburn or ulcer medicines such as antacids, cimetidine (Tagamet), ranitidine (Zantac), sucralfate (Carafate), and omeprazole (Prilosec)
  25. herbal remedies such as dong quai, garlic, ginkgo biloba, ginseng, coenzyme Q10, St. John's wort, alfalfa, arnica, capsicum, chamomile, dandelion, fenugreek, horse chestnut, licorice, nettle, passion flower, red clover, sweet clover, pau d'arco, agrimony, black cohosh, feverfew, ginger, willow, and goldenseal
  26. immunosuppressant medicine such as azathioprine (Imuran)
  27. MAO inhibitor antidepressants such as phenelzine (Nardil), tranylcypromine (Parnate), and isocarboxazid (Marplan) (Do not take this medicine and an MAO inhibitor within 14 days of each other.)
  28. medicine for low blood sugar such as diazoxide (Hyperstat) and glucagon
  29. medicines used to treat cancer such as capecitabine (Xeloda), cyclophosphamide (Cytoxan), ifosfamide (Ifex), fluorouracil (Adrucil, 5-FU), flutamide (Eulexin), mercaptopurine (Purinethol, 6-MP), and tamoxifen (Nolvadex)
  30. methylphenidate (Ritalin, Concerta, Metadate)
  31. quinine
  32. raloxifene (Evista)
  33. sleeping pills such as chloral hydrate
  34. SSRI antidepressants such as fluoxetine (Prozac, Sarafem), fluvoxamine (Luvox), paroxetine (Paxil), trazodone (Desyrel) and sertraline (Zoloft)
  35. thyroid medicine such as liothyronine (Cytomel, Triostat), levothyroxine (Levothroid, Levoxyl, Synthroid, Unithroid), methimazole (Tapazole), propylthiouracil, and thyroid (Armour Thyroid, Nature-Throid)
  36. vitamins such as vitamin K, vitamin E, and large amounts of vitamin C.
 Discuss your diet with your health care provider. Foods that have moderate to high amounts of vitamin K include brussel sprouts, kale, green tea, asparagus, avocado, broccoli, cabbage, cauliflower, collard greens, liver, soybean oil, soybeans, certain beans, mustard greens, peas (blackeyed peas, split peas, chick peas), turnip greens, parsley, green onions, spinach, and lettuce.
 Do not drink alcohol while you are taking this medicine. Talk with your health care provider about this.
 Keep a list of all your medicines (prescription, nonprescription, supplements, natural remedies, and vitamins) with you. Be sure that you tell all health care providers who treat you about all the products you are taking.
How should I store this medicine?
 Store this medicine at room temperature. Keep the container tightly closed. Protect it from heat, high humidity, and bright light.
Prothrombin Time Test (PT) and INR
What is the prothrombin time test?
 The prothrombin time, or PT, test measures the time it takes your blood to form a clot. This test is also often called protime.
 The results of the prothrombin time test may vary from lab to lab, so health care providers use a ratio called the INR (international normalized ratio) to be able to account for the differences.
Why is this test done?
 The PT/INR is usually done to measure the effect of blood-thinning medicines (anticoagulants), such as warfarin (Coumadin).
 If you have a medical condition such as atrial fibrillation or deep vein thrombosis, or have had a heart valve replaced, your blood is more likely to form clots. Clots can block blood vessels and possibly cause a heart attack or stroke. Your health care provider may prescribe a blood thinner to help prevent clots. It's very important to measure the effect of a blood thinner with this test. The medicine should keep the blood just thin enough to prevent clots. If the blood is too thin, you may bleed too easily.
 The prothrombin time test may also be done if you have abnormal bleeding or clotting.
How do I prepare for this test?
  1. You may need to avoid taking certain medicines before the test because they might affect the test result. Make sure your health care provider knows about any medicines, herbs, or supplements that you are taking. Don't stop any of your regular medicines without first consulting your health care provider.
  2. If you are taking warfarin (Coumadin), having different amounts of vitamin K in your diet from day to day can affect your test results and the Coumadin dosage that you need. For example, leafy green vegetables, such as spinach, and oils such as canola oil and soy bean oil, are some of the foods that have high amounts of vitamin K. If you are on warfarin, you should eat a healthy balanced diet with about the same amount of vitamin K each day. Follow your health care provider's instructions for your diet.
How is the test done?
 A small amount of blood is taken from your arm with a needle. The blood is collected in tubes and sent to a lab.
 Having this test will take just a few minutes of your time. There is no risk of getting AIDS, hepatitis, or any other blood-borne disease from this test.
How will I get the test result?
 Ask your health care provider when and how you will get the result of your test.
What does the test result mean?
 The normal PT range is 11 to 14 seconds. The normal range may vary slightly from lab to lab. Normal ranges are usually shown next to your results in the lab report.
 A PT value higher than normal means your blood is taking longer than usual to form a clot. This prolonged PT may happen if:
  1. You are taking warfarin.
  2. You have liver disease.
  3. You need more vitamin K.
  4. You have an inherited blood disorder.
  5. You have had a lot of heavy bleeding recently.
 The normal value for the INR is 1.0
 The INR is used to adjust the dose of warfarin. The desired INR will vary depending on what condition is being treated. Most cases the therapeutic range is between 2.0 – 3.0 with less than 2.0 indicating too little Coumadin on board (risk of clotting) while an INR greater than 3.0 indicates too much Coumadin (risk of bleeding).
What if my test results are not normal?
 Test results are only one part of a larger picture that takes into account your medical history and current health. Sometimes a test needs to be repeated to check the first result. Talk to your health care provider about your result and ask questions.
 If your test results are abnormal, ask your health care provider:
  1. if you need additional tests
  2. what you can do to work toward a normal value
  3. when you need to be tested again.

Sincerely:
Joseph Saponaro, MD, DABIM, FACP, CPI, CCI, CCTI, CCRC, CCRP
PI (Principal Investigator), DSI (Drug Study Institute)
Board Certified Internist, JPMC (Jupiter Preventive Medicine Center)
DABIM (Diplomat American Board of Internal Medicine)
FACP (Fellow American College of Physicians)
CPI (Certified Physician Investigator) by the AAPP (American Academy of Pharmaceutical Physicians)
CCTI (Certified Clinical Trial Investigator) by the ACRP (Association of Clinical Research Professionals)
CCI (Certified Clinical Investigator) by the DIA (Drug Information Association)
CCRC (Certified Clinical Research Coordinator) by the ACRP (Association of Clinical Research Professionals)
CCRP (Certified Clinical Research Professional) by SoCRA (Society of Clinical Research Associates)
Member, SIMPD (Society for Innovative Medical Practice Design)
Member, ACPM (American College Preventive Medicine)
Ethics Committee Member, Jupiter Medical Center
IRB Member, Jupiter Medical Center
Founder, CertifiedResearchers.com