Warfarin (Warfarin Sodium) - Summary

WARFARIN SUMMARY

Warfarin sodium is an anticoagulant which acts by inhibiting vitamin K-dependent coagulation factors.

Warfarin sodium tablets are indicated for the prophylaxis and/or treatment of venous thrombosis and its extension, and pulmonary embolism.

Warfarin sodium tablets are indicated for the prophylaxis and/or treatment of the thromboembolic complications associated with atrial fibrillation and/or cardiac valve replacement.

Warfarin sodium tablets are indicated to reduce the risk of death, recurrent myocardial infarction, and thromboembolic events such as stroke or systemic embolization after myocardial infarction.

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NEWS HIGHLIGHTS

Media Articles Related to Warfarin

Alternative to Warfarin May Cut Risk of Bleeding
Source: MedicineNet Atrial Fibrillation Specialty [2009.11.16]
Title: Alternative to Warfarin May Cut Risk of Bleeding
Category: Health News
Created: 11/15/2009 4:10:00 PM
Last Editorial Review: 11/16/2009

Oldest Heart Patients May Get Most From Warfarin
Source: MedicineNet Atrial Fibrillation Specialty [2009.09.01]
Title: Oldest Heart Patients May Get Most From Warfarin
Category: Health News
Created: 8/31/2009 4:10:00 PM
Last Editorial Review: 9/1/2009

Aspirin as effective as warfarin and safer in stroke prevention
Source: The Doctors Lounge - Neurology
Intracranial stenosis is caused by atherosclerosis - fatty deposits that build up on the inner walls of the arteries and restrict blood flow.

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Published Studies Related to Warfarin

Thrice weekly warfarin administration in haemodialysis patients. [2009.10]
BACKGROUND: Medication adherence in haemodialysis patients is often challenging due to a high pill burden, complex and dynamic medication regimens and limited patient self-interest in care. The purpose of this study was to investigate the time within target INR and safety profile of thrice weekly warfarin administration in haemodialysis patients with a clinical indication for anticoagulation and documented nonadherence to medications... CONCLUSION: In this pilot study, thrice weekly warfarin appears to be a safe and feasible dosing strategy in a select patient population. A randomized controlled trial of thrice weekly warfarin is warranted.

Dabigatran versus warfarin in patients with atrial fibrillation. [2009.09.17]
BACKGROUND: Warfarin reduces the risk of stroke in patients with atrial fibrillation but increases the risk of hemorrhage and is difficult to use. Dabigatran is a new oral direct thrombin inhibitor... CONCLUSIONS: In patients with atrial fibrillation, dabigatran given at a dose of 110 mg was associated with rates of stroke and systemic embolism that were similar to those associated with warfarin, as well as lower rates of major hemorrhage. Dabigatran administered at a dose of 150 mg, as compared with warfarin, was associated with lower rates of stroke and systemic embolism but similar rates of major hemorrhage. (ClinicalTrials.gov number, NCT00262600.) 2009 Massachusetts Medical Society

Use of Warfarin in People with Low Glomerular Filtration Rate or on Dialysis. [2009.09.09]
Abstract Atrial fibrillation, venous thromboembolism, and access malfunction are common clinical problems in dialysis patients that prompt consideration of warfarin therapy. Atrial fibrillation appears to be more common in people with low glomerular filtration rate (GFR) or on dialysis than in the general population, but the risk of stroke in this population is not known...

Practical application of the 10-mg warfarin initiation nomogram. [2009.09]
Initiation of warfarin therapy is a clinical challenge. A 10-mg warfarin initiation nomogram was recently validated in a randomized controlled trial... The 10-mg nomogram effectively results in an early therapeutic international normalized ratio with a good safety profile in 'real-life' daily practice.

Percutaneous closure of the left atrial appendage versus warfarin therapy for prevention of stroke in patients with atrial fibrillation: a randomised non-inferiority trial. [2009.08.15]
BACKGROUND: In patients with non-valvular atrial fibrillation, embolic stroke is thought to be associated with left atrial appendage (LAA) thrombi. We assessed the efficacy and safety of percutaneous closure of the LAA for prevention of stroke compared with warfarin treatment in patients with atrial fibrillation... INTERPRETATION: The efficacy of percutaneous closure of the LAA with this device was non-inferior to that of warfarin therapy. Although there was a higher rate of adverse safety events in the intervention group than in the control group, events in the intervention group were mainly a result of periprocedural complications. Closure of the LAA might provide an alternative strategy to chronic warfarin therapy for stroke prophylaxis in patients with non-valvular atrial fibrillation. FUNDING: Atritech.

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Clinical Trials Related to Warfarin

Duloxetine - Warfarin Pharmacodynamic Study [Completed]
To evaluate the blood clotting effects of multiple doses of warfarin at steady state when taken at the same time as multiple doses of duloxetine as measured by changes in the International Normalised Ratio.

Access II - Trial of Warfarin to Prevent Malfunction of Haemodialysis Catheters [Completed]
This study examines whether low intensity, dose adjusted warfarin prolongs the time to mechanical failure of hemodialysis catheters without resulting in an unacceptable rate of bleeding.

A Study Testing the Effect and Safety of Casopitant (GW679769) While Taking Warfarin in Healthy Human Volunteers [Completed]
GW679769 may affect liver enzymes that metabolize warfarin. This study is designed to test the extent of the GW679769 affect on Warfarin levels in humans.

Warfarin After Anterior ST-Elevation Myocardial Infarction [Completed]
Following severe heart attacks involving the front wall of the heart (anterior myocardial infarction), patients are at risk of developing blood clots in the main pumping chamber that can cause a stroke. In the past, studies have shown that a blood thinner (warfarin) can decrease the risk of stroke and clot formation if administered to patients after an anterior myocardial infarction.

However, in today's current practice, certain heart attack patients are commonly treated with two blood-thinning medications (aspirin and clopidogrel) to prevent recurrent heart attacks.

Thus, a clinical problem is created as physicians are not clear how to treat patients after an anterior myocardial infarction who are at risk of a clot but require aspirin and clopidogrel to keep their blood vessels open. Adding warfarin to the combination of aspirin and clopidogrel will possibly decrease the risk of stroke but increase the risk of bleeding. Currently, there is no good evidence to help guide physicians. As demonstrated by a survey done at the Hamilton Health Sciences, there is a fifty/fifty split between physicians who use dual (aspirin and clopidogrel) versus triple (aspirin, clopidogrel, and warfarin) therapy in the treatment of similar patients as described above.

The purpose of this study is to address the bleeding and stroke complications in patients after a severe anterior myocardial infarction. Half of the eligible patients will receive dual therapy and half will receive triple therapy. We will compare the incidence of stroke, blood clots, and bleeding complications between the two groups at 3 months.

Oral Vitamin K for Warfarin Associated Coagulopathy [Active, not recruiting]
Excessive prolongation of the international normalized ratio (INR) occurs frequently in patients taking warfarin; in fact, about one in six INR values is above the desired range. Excessive prolongation of the INR is clinically important because the risk of bleeding approximately doubles for each one point increase in the INR beyond the usual therapeutic range. Thus, treatment strategies which rapidly and reliably lower an excessively prolonged INR into the desired range have the potential to reduce bleeding. When taken by patients with INR values between 4. 5 and 10, a small dose of oral vitamin K (1 mg to 2. 5mg) reduces the INR into the desired INR range in about 75% of cases within 24 hours of its administration. If warfarin is simply withheld, and no vitamin K is given, about 25% of patients will have an INR in the desired range at 24 hours. However, vitamin K is rarely given to such patients. In a recent survey carried out by our group, less than 20% of such patients would have been given low dose oral vitamin K by a group of physicians who regularly supervise warfarin therapy.

The most common treatment for excessive prolongation of the INR is to simply withhold warfarin and allow the INR to fall into the therapeutic range. Although this strategy is effective its safety has never been adequately examined. In fact, recent evidence suggests that patients with INR values of more than 6. 0 who are treated with simple warfarin withdrawal have a risk of major bleeding of 4% in the two weeks after they develop their prolonged INR.

When asked why they did not give oral vitamin K to a non-bleeding patient who has an excessively prolonged INR, physicians generally give one of three reasons: (1)They are not convinced that oral vitamin K reduces bleeding. (2) They are concerned that oral vitamin K may cause thrombosis. (3) In contrast with simply withholding warfarin, giving oral vitamin K requires a patient to visit the physician, and the physician must have a supply of vitamin K.

We hypothesize that the routine practice of not administering oral vitamin K to patients with excessively prolonged INR values is causing patients to have major, life-threatening and fatal bleeds. To convince physicians that oral vitamin K should be administered to all non-bleeding patients with INR values of more than 4. 5, we propose a study which we anticipate will demonstrate that oral vitamin K reduces bleeding, does not cause thrombosis, and can be administered at home without direct physician supervision.

To accomplish these goals, we propose a multinational, double-blind, placebo-controlled trial. We will randomize patients with INR values between 4. 5 and 10. 0 to receive 1. 25 mg of oral vitamin K or placebo and follow them for bleeding and thrombosis. Patients with INR values of more than 10. 0 will receive a single 1. 25 mg dose of oral vitamin K.

Successful completion of this study will establish a treatment standard supported by clinical data which will, in turn, change the way that patients taking warfarin who present with an excessively prolonged INR are treated.

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PATIENT REVIEWS / RATINGS / COMMENTS

Warfarin review by 44 year old female patient
		Rating
Overall rating:
Effectiveness:		Considerably Effective
Side effects:		Moderate Side Effects
		Treatment Info
Condition / reason:		heart condition
Dosage & duration:		3 mg. warfarin taken 1 time daily for the period of 3 years
Other conditions:		none
Other drugs taken:		none
		Reported Results
Benefits:		Taking 3 mg of warfarin sufficiently thinned my blood so that I did not find it difficult to do everyday tasks. I immediately felt better after I started the regimen in the spring of 2003. My cough went away and I had a lot more energy. I took this regimen for about 3 years, everyday. I also found it easier to concentrate and think (what was I doing before it???) It was as if my brain cleared up or something. I breathed easier and I was more willing to tackle regular household chores. I worked over 50 hours/week before and during this treatment.
Side effects:		The side effects of warfarin on me did not become apparent until a couple of years later. I started feeling weak and I bruised easily. I acquired more broken blood vessels/capillaries veins in my feet and calves. I was tired and started feeling cranky. I stopped taking warfarin for 6 months but then went back to it after I had the old feeling of "thick" blood. During the 6 months that I wasn't taking warfarin, I felt better, had more energy. But then the downside: my blood was getting too thick and I was starting to get headaches. So I went back on it. This time my doctor said I might have to increase dosage to 4 mg. since I hadn't been taking the warfarin. However, when I had my thrombin checked, I was okay at 3 mg.; I took this for another 3 months and then started feeling the old way and quit again. The same scenario was repeated (started feeling like I had "thick" blood and now I had increasingly bad headaches). I went back on 3 mg. of warfarin in August of this year but only took them for 3 months. Then I started a vitamin/mineral/COQ10 regimen and stuck with it and am still doing that. I credit most of the perfect blood feeling (for lack of a better term) to Vitamin E and the fact that I also changed my diet. I try to eat a lot of veggies and fruits, and I have been a vegetarian for almost two years (not super strict - but I feel disgusted about eating meat and therefore never eat it unless it is buried in some food. I do eat salmon and tuna. The final straw for me with warfarin was that I started feeling really mad about things. The littlest things would make me angry, anger that was way out of proportion to the incident. When my teenaged daughter started crying after I ripped into her for staying longer at a social visit, and I heard my words echoing in my house, I knew that was it. I quit warfarin and started taking 81 mg. of aspirin daily (I had a headache every morning after I went off warfarin). I started the vit./min. regimen in November, gradually adding supplements as I learned about their benefits, but it wasn't until 3-4 weeks ago that I realized I wasn't having any headaches and I was able to stop taking 81 mg. of aspirin. Also, since starting the stricter diet and the vit./min. supplements (also some herbs), I have not had an anger "fit" (of course, I am also more prone to control my anger because I really didn't like how I had been), I do not feel depressed. I have told everyone in my family about this because it seems so remarkable. Why didn't the doctors tell me?
Comments:		Treatment consisted of simply taking 3 mg. of warfarin daily and getting my blood thrombin checked every two months. I was not a very good patient about getting my blood thr. checked so I'm sure when I was feeling weak and bruised/bled so easily, my blood was getting too thin. And then when I would quit the warfarin for several weeks, sometimes months at a time, my blood would get too thick. I really like my doctor though, because he tells me to do what makes me feel best, and I think that's smart advice. I must say add that I always loved the feeling of donating blood before I took warfarin because it gave me the same feeling as I initially had with warfarin (at the very beginning of my treatment). I would like to donate blood now but they don't let me because I don't weigh enough (which makes no sense at all). Couldn't they take less blood? Who determined how much blood you can give anyway?