WARFARIN – PATIENT EDUCATION AND ADVICE
What is Warfarin?
Anticoagulant helps prevent clots in the blood from forming
Uses
Prevention of DVT / PE, use in people with heart valves, AF or atrial flutter, stroke/TIA
How does it work?
Vitamin K antagonist for blood factors made in the liver
How long does it take to work?
It starts working after 24hrs but does not get full effect until after 72-96hrs need to use heparin for the
first 4-5 days
A single dose works for 2-5 days however it is important to take the doses as prescribed to maintain the
correct level in the blood
What dose do I take?
5mg is usual starting dose (3mg if elderly or malnourished or liver failure or CCF ot high INR to begin with)
Most people start on 5mg once a day for the first 2 days and this dose is altered according to a blood test
called INR. This blood test basically measures how thick/thin your blood is. We want your INR to be
somewhere between 2-3. (or 2.5-3.5 if valve)
Daily INR until 2x consecutive days within therapeutic range and then every 48hrs, adjusting the dose to
maintain within therapeutic range...
If the INR is too low = thick blood
If the INR is too high = thin blood
You will not know that the INR is too high or too low and therefore you need to have INR blood tests very
regularly at the beginning to make sure it stays within the normal range
Blood tests and monitoring
Daily every 2nd day every few days weekly eventually every month
What about drug interactions?
There are many drug interactions macrolides, steroids, antibiotics, amiodarone – there are many!!
Always let your pharmacist know when getting OTC meds
Always tell doctors you are on it some people like to have a medical alert bracelet for this purpose
Never take alternative medicines unless you are sure they will not interact St Johns Wort commonly
reduces the effect of warfarin greatly, Ginkgo increases
Missing a dose
Take as soon as you remember if on the day you were meant to take it – notify your dr
If you have missed a dose and forget to take on the day don’t take extra on the next day – just take the usual
dose
Medications you should AVOID;
NSAIDs and aspirin
Vitamin K, C, E and other high potency vitamins multivitamins are OK if low potency
Certain laxatives – ask pharmacist
Antacids just before taking warfarin Mylanta etc
Foods and Warfarin
Cruciferous veges
etOH
Liver
Don’t make drastic changes to your diet – everything in moderation
When to see a doctor straight away
Bleeding from the gums or bruising excessively
A cut that does not stop bleeding within 10mins
Bruises that appear suddenly and for no reason
Coughing up or vomiting blood / black stuff
Bowel motions that are red or look like tar
If you have a bad fall, injure yourself in sports or hit your head even if you seem OK