Warfarin Therapy

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Why is this medicine prescribed? Warfarin is used to prevent formation of blood clots and existing clots from growing larger. It is often prescribed for patients with certain types of irregular heartbeat, or who have experienced a heart attack or heart valve replacement surgery. Warfarin works by stopping the formation of substances that cause clots.

This medicine is sometimes prescribed for other uses; consult your doctor or pharmacist for more information.

How should this medicine be taken?Follow the directions on the medication label. Take your tablet at the same time once daily. There are different brands of warfarin available (e.g. Marevan®, Coumadin®). Do not switch brands as they may have different effectiveness. The table below shows the strength and description of the tablets:

Strength Color Front view of tablet Back view of tablet

1mg Brown

3mg Blue

5mg Pink

Do not stop taking warfarin without consulting your doctor.

What should I do if I forget to take a dose?Take the missed dose as soon as you remember, if it is within 8 hours of your usual time. Do not take the dose if it has been more than 8 hours. Continue to take your warfarin at the usual time the next day. Do not double the dose. Doubling the dose may cause bleeding. Record the date of the missed dose and inform your doctor at the next visit.

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What are the special precautions?MedicationsMany medications interfere with the effectiveness of warfarin. It is important to inform your doctor or pharmacist if you are taking other medications including non-prescription, traditional and herbal medications. These include:• antacids• cough or cold remedies• gastric ulcer medicine• laxatives• pain killers (e.g. aspirin and other NSAIDS)• vitamin supplements (Vitamin K)• ginkgo biloba supplements

It is advisable not to take any Jamu, Chinese or Ayurvedic medicine, as their effects on warfarin are unpredictable.

PregnancyWarfarin can cause birth defects. Inform your doctor and pharmacist if you are pregnant or intend to conceive.

SurgeryIf you are having surgery (including dental surgery) inform the doctor or dentist that you are taking warfarin. Your doctor may tell you to stop taking warfarin a few days before your procedure to avoid excessive bleeding.

AlcoholAvoid excessive alcohol intake. It is advisable not to take more than 5 cans of beer or more than 1 bottle of wine per week.

Daily ActivitiesBe careful when using razors and other sharp objects.

Avoid contact sports (e.g. football, rugby, martial arts) or activities that may cause you to be injured.

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InjuriesShould you get a minor injury, wash and apply pressure to the area until bleeding stops (this may take up to 10 minutes). Please seek medical attention immediately if there is profuse bleeding from the wound or if you sustain head injuries. Continue to apply pressure to the wound while awaiting help.

What side effects can this medicine cause?The most common side effect of warfarin is bleeding. Please inform your doctor should you encounter any of these.

BruisingYou may be bruised easily should you fall or knock against something. DO NOT rub or massage the area. Please seek medical attention if the bruise becomes larger or does not reduce in size, or if you get bruises for no apparent reason.

BleedingPlease seek medical attention should you experience the following symptoms:

• Bleeding from ears, nose and gums (use a soft toothbrush for brushing teeth)• Vomiting of blood (which may look like coffee grounds or fresh blood• Unexplained severe abdominal pain• Red spots on the skin• Unusual pain or swelling (e.g. in the joints)• Blood in your urine• Heavy menstrual bleeding• Rectal bleeding• Black, sticky stool

What special dietary instructions should I follow?Discuss your diet with the doctor. Do not make any major changes to your consumption of food containing vitamin K, such as liver, green leafy vegetables and broccoli, as this may alter the effects of warfarin.

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Vitamin K content in common food items

AMOUNT OF VIT K

LOW MODERATE HIGH

FRUITS Apple,

Banana,

Orange,

Pear

– –

FATS & OILS Corn oil,

Sesame oil,

Sunflower oil

–

Canola oil (15ml - 1 tablespoon),

Soybean oil

(15ml - 1 tablespoon)MEAT & MEAT

PRODUCTS Bacon, Beef & Pork,

Chicken (breast)

Chicken liver (100g), Pork liver (100g)

Beef liver (100g),

Egg yolk

MILK & DAIRY PRODUCTS Butter,

Cheese, Milk

– –

CEREALS & GRAIN

PRODUCTS Bread (4 slices),

Cereals, Rice (½ cup)

– –

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BEVERAGES (½ cup unless

otherwise stated)

Coffee, Cola,

Tea,

Fruit juice

Green tea (2 tea bags)

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VEGETABLES (½ cup unless

otherwise stated)

Carrot, Celery,

Corn,

Mushroom,

Potato,

Tomato

Asparagus,

Cabbage, Cauliflower,

Lettuce

Broccoli,

Brussels sprouts,

Chinese Kai Lan / Kale,

Parsley,

Seaweed,

Spinach

LEGUMES Soy milk Green bean,

Soybean (2

dessertspoons)

Chick peas (2 dessert spoons),

Lentils (10ml - 2 dessertspoons)

TofuSUPPLEMENTS – Cod liver

oil (15ml - 1 tablespoon)

Multivitamins with Vitamin K

(1 tablet)

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How should warfarin be stored?Store it in a cool and dry place, away from light. Keep out of reach of children.

What else should I know?If you are consulting another doctor, dentist or pharmacist, always inform them that you are taking warfarin.

As you are taking warfarin, you need to come back regularly for blood tests. During each visit with your doctor, a blood test will be ordered to check your International Normalised Ratio (INR), which reflects the intensity of anticoagulation. Therefore, it is important for you to come for every appointment to ensure that the warfarin is dosed appropriately. Always make another appointment if you miss one.

You should consider carrying an identification card (Medik Awas) to indicate that you are taking warfarin. This is important especially during an emergency or if you are unconscious. Consult your pharmacist or doctor on how to obtain this card.

All information is valid at the time of printing (February 2014) and subject to revision without prior notice.

2 Simei Street 3 Singapore 529889 Tel: 6788 8833 Fax: 6788 0933

Reg No 198904226R

For appointments and enquiries, please call the CGH Appointment Centre at

Tel: (65) 6850 3333

CGH Appointment Centre operating hours: 8.30 am to 8.00 pm (Monday to Friday)

8.30 am to 12.30 pm (Saturday & Sunday) Closed on Public Holidays

For more information, please visit http://www.cgh.com.sg

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