Warfarin Basics&Patient Education :Warfarin Basics&Patient Education 2009 Approx. time 30 min


Objectives :Objectives After completing this activity, the participant will be able to: Explain: Basic characteristics of warfarin’s effect Laboratory monitoring for warfarin Effects of diet on warfarin Common adverse effects Provide essential elements of warfarin patient education


What is it? :What is it? Generic name = warfarin sodium Brand = Coumadin® Branded Generic = Jantoven® Effects uncovered by Midwest farmers, 1920s Isolated from spoiled sweet clover, 1939 by the Wisconsin Alumni Research Foundation Used as rat poison Commercially for human treatment, 1955


What makes warfarin different? :What makes warfarin different? Highly variable response from patient to patient No standard way to estimate the dose needed Requires frequent blood tests (PT/INR) HIGH RISK MEDICATION Small difference between ineffective levels & toxic levels Frequent dosing changes based on PT/INR Numerous interactions Dietary habits affect the response & dose


General Characteristics of Warfarin :General Characteristics of Warfarin Slows the normal clotting process Vitamin K is needed to produce 4 clotting proteins Warfarin blocks activity of vitamin K Reduces the amount of clotting proteins Technically, it does not “thin” the blood Does not dissolve clots Prevents extension of existing clots Prevents formation of new clots, when used at the appropriate levels


General Characteristics of Warfarin :General Characteristics of Warfarin Effect builds slowly 1 week or more to see maximal effect Long-lasting effects Stop taking prior to surgical procedures Up to 5 days are needed to achieveINR < 1.5 Vitamin K is the antidote for warfarin


Vitamin K and Warfarin: Opposites :Vitamin K and Warfarin: Opposites Vitamin K is needed in the blood’s normal clotting processes Lowers INR by making more clotting factors Warfarin blocks the action of vitamin K Pushes INR higher Blood will still clot, but at a slower rate Slows down the formation of harmful clots


Blood Tests: How “Thin”? :Blood Tests: How “Thin”? Prothrombin Time (PT) Measure of time for blood to coagulate (seconds) International Normalized Ratio (INR) A calculation using PT adjusts for lab-to-lab variability of testing reagents The gold standard for evaluating warfarin’s effect on clotting


Blood Tests: How Often? :Blood Tests: How Often? Inpatients must have baseline INR before giving the first dose INR on admission for those already taking warfarin chronically INR measurements daily as inpatient Exception for BHS patients on stable doses


Blood Tests: How Often? :Blood Tests: How Often? Outpatients For new patients, 1 – 2 times weekly When INRs are consistent & stable Extend to weekly, or every other week No less frequent than every 4 weeks for stable patients


Efficacy/Safety Relationship :Efficacy/Safety Relationship For persons not taking warfarin, normal INR range is 1.0 – 1.2 Very different when taking warfarin INR too low (ex. 4.5) Increased risk for major bleeding events


Slide 13:Hylek EM, et al. Ann Internal Med 1994; 120:897-902 Too Low Too High


Efficacy/Safety Relationship :Efficacy/Safety Relationship INR range depends upon indication 2.0 – 3.0 Stroke prevention in persons with AFib, AFlut DVT/PE treatment Hip or knee replacement 2.5 – 3.5 Some mechanical heart valves Some hypercoagulable conditions (genetics), or people who have developed clots at lower INRs


Factors Affecting Warfarin Dose :Factors Affecting Warfarin Dose Age Drug Interactions Diet Lifestyle / Habits Adherence to Therapy


Age :Age Older patients typically need less warfarin First doses no larger than 5mg for inpatients 75yo or older Maximum first dose of 10mg for all younger inpatients


Other Medications w/ Warfarin :Other Medications w/ Warfarin MANY different medication interactions Some medications will cause warfarin to accumulate in the bloodstream Increased chances of bleeding Some decrease warfarin’s effect Antibiotics commonly interact with warfarin


Diet Considerations :Diet Considerations Certain foods, especially green leafy vegetables, have large amounts of vitamin K Eating too much of these at one time may reverse the benefit of the warfarin Important to note which foods are high in vit K


Some Foods High in Vitamin K :Some Foods High in Vitamin K Green leafy vegetables Broccoli, brussels sprouts, cabbage, collard greens, endive, green scallion, kale, spinach, turnip greens, watercress Salad Oils canola, salad, and soybean oils mayonnaise Liver


Lifestyle / Habits :Lifestyle / Habits Alcohol use Acute use (>2 drinks/day) increases INR Exercise Increased exercise may decrease INR Smoking or Chewing Tobacco Increased use may decrease INR (vit K in tobacco) Smoking cessation may increase INR


Essential Patient Education :Essential Patient Education Recognize names (warfarin = Coumadin® = Jantoven®) Reason to take it (indication) Discuss INR and frequency of monitoring How & when to take the doses Signs and symptoms of bleeding; what to do Counsel re: interactions, herbals, med. changes Role of diet and vitamin K Role of lifestyle choices (tobacco, alcohol) Medic Alert bracelet/ID


Know the Names :Know the Names Warfarin is the generic name Two brand names are Coumadin®, Jantoven® Patients will never use more than one of these at the same time


Why Take Warfarin :Why Take Warfarin Atrial Fibrillation or Previous Stroke Warfarin reduces the chances of having a stroke associated with AFib Better than aspirin at preventing stroke caused by Atrial Fibrillation


Why Take Warfarin :Why Take Warfarin Deep Vein Thrombosis (DVT) and Pulmonary Embolus (PE) Warfarin stops the clot from getting larger Reduces the chance of repeat clot The body’s normal processes break down the clot over time


Why Take Warfarin :Why Take Warfarin After Hip or Knee Replacement Warfarin reduces chance of DVT Abnormal Coagulation Profile Genetic predisposition to form harmful clots Warfarin can reduce the chances of forming harmful clots like DVT/PE


Unlike Any Other Medication :Unlike Any Other Medication Not the same dose for everyone Small difference between benefit & risk Too much = side effects, bleeding Too little = ineffective, clots Many different things affect the way your body responds to the warfarin


General Instructions :General Instructions Take warfarin every evening If you miss a dose If still dark outside, take it when you remember If the sun is up the next morning, skip it Record the date, inform provider at next INR Tell all care providers you take warfarin


General Instructions :General Instructions Take only the doses prescribed Doses may change based on the blood test results Use a calendar, pillbox, or some other way to keep track Have blood tests as instructed


INR Test :INR Test INR blood test is the only way to tell how well the medication is working At first, these tests are frequent At least once each month is recommended INR is a measure of blood clotting INR too high you may need less warfarin Too low, you may need more warfarin


Target INR :Target INR Target Range is where Therapeutic effect is maximized Benefit of clot prevention Side effects are minimized Less chance of bleeding & bruising Usual INR target is 2.0 – 3.0 May be 2.5 – 3.5 for heart valve replacements


Drug Interactions :Drug Interactions Changes to existing therapy should always be reported to AC provider Starting a new drug Stopping an old drug Increase/decrease in dose Herbals or alternative medicines Antibiotics


Other Medication :Other Medication Medications to Avoid : NSAIDs (Aleve, Advil, Ibuprofen, Naproxen) Aspirin (unless prescribed by doctor) Increase risk of stomach bleeding Always check with pharmacist or doctor before starting a non-prescription drug


Adverse Effects :Adverse Effects Bleeding Related to INR levels; can occur at any level Bleeding risk increases when INR > 4.5 Antiplatelet agents increase bleeding risk Aspirin, Plavix®, NSAIDs Sites of bleeding Gastrointestinal, Nose, Gums, Intracranial


Signs of Warfarin Excess :Report unusual bleeding Blood in stool (black, tarry color) Blood in urine (brown, red/pink color) Excessive nose bleeds/bleeding gums Persistent oozing from superficial injuries Excessive menstrual bleeding Unusual bruising (large areas) Signs of Warfarin Excess


Get Immediate Treatment! :Get Immediate Treatment! Red or dark brown urine Red or black stool Vomiting blood, or coffee ground material Sudden severe headache Lightheadedness, fainting Severe abdominal or back pain


Notify Doctor :Notify Doctor Frequent or heavy nose bleeds Unusual, excessive bruising Prolonged bleeding of cuts Bleeding gums


Diet Advice for Patients :Diet Advice for Patients Don’t change your diet when starting warfarin Try to maintain consistency Be aware of foods high in vitamin K Limit portion size of high vitamin K foods Consult your provider before making big changes to your diet


Diet and Warfarin :Diet and Warfarin Completely avoidingvitamin K containing foods isNOT recommended


Other Instructions :Other Instructions Avoid pregnancy Avoid alcohol in excess Get refills on time, don’t run out of warfarin MedicAlert ID or carry medication list If you smoke, tell your provider if you quit


Resources :Resources On Demand program on hospital TV “Patient’s Guide to Warfarin” Booklet ordered from Patient Education Dept “The Warfarin Lifestyle” Group education sessions Monthly in York; call for Gettysburg sessions For schedule, call 1-800-840-5905 Online www.mybloodthinner.org www.ahrq.gov/consumer/coumadin.pdf 1-800-COUMADIN


Summary :Summary Warfarin is a unique medication Requires patient education for safe use Use handouts in combination with verbal instructions Properly educated patients should Understand the need for INR testing Recognize adverse effects Know what to do


Slide 42:To obtain full credit, please complete the quiz associated with this activity. Shawn Slenker, PharmD WellSpan Anticoagulation Services sslenker@wellspan.org