Warfarin chemical structure3mg (blue), 5mg (pink) and 1mg (brown) warfarin tablets (UK colours)
Find information on thousands of medical conditions and prescription drugs.

Warfarin

Warfarin (also known under the brand names of Coumadin® and Marevan®) is an anticoagulant medication that is administered orally. It is used for the prophylaxis of thrombosis and embolism in many disorders. Its activity has to be monitored by frequent blood testing for the international normalized ratio (INR). It is named for the Wisconsin Alumni Research Foundation. more...

Home
Diseases
Medicines
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
Warfarin
Wellbutrin
Westadone
Winstrol
Wydase
Wymox
X
Y
Z

Warfarin was originally developed as a rat poison, and is still widely used as such, although warfarin-resistant rats are becoming more common.

Mechanism of action

Normally, vitamin K is converted to vitamin K epoxide in the liver. This epoxide is then reduced by the enzyme epoxide reductase. The reduced form of vitamin K epoxide is necessary for the synthesis of many coagulation factors (II, VII, IX and X, as well as protein C and protein S). Warfarin inhibits the enzyme epoxide reductase in the liver, thereby inhibiting coagulation.

Uses

Medical use

Warfarin is given to people with an excessive tendency for thrombosis. This can prevent growth or embolism (spread) of a thrombus. Common indications for warfarin use are atrial fibrillation, artificial heart valves, deep venous thrombosis and pulmonary embolism.

Therapeutic drug monitoring is required, as warfarin has a very narrow therapeutic index, which means the levels in the blood that are effective are close to the levels that cause bleeding. Dosing of warfarin is further complicated by the fact that it is known to interact with many other medications and other chemicals which may be present in appreciable quantities in food (including caffeine and ascorbic acid). These interactions range from enhancing warfarin's anticoagulation effect to reducing the effect of warfarin.

As a result, it is easy to over- or under-coagulate the patient. Warfarin's effects must be closely monitored: this is done by using the INR. Initially, checking may be as often as twice a week; the intervals can be lengthened if the patient manages stable therapeutic INR levels on a stable warfarin dose.

When initiating warfarin therapy ("warfarinisation"), the doctor will generally decide how strong the anticoagulant therapy needs to be. A common target INR level is 2.0-3.0, though it varies from case to case.

The new oral anticoagulant ximelagatran (Exanta®) does not require INR monitoring, and was expected to replace warfarin to a large degree when introduced; however, it has run into approval problems and currently (2005) it is not clear if or when it will ever become available for general use.

Pesticide use

Warfarin is used as a rodenticide for controlling rats and mice in residential, industrial, and agricultural areas. It is both odorless and tasteless. It is effective when mixed with food bait, because the rodents will return to the bait and continue to feed over a period of days, until a lethal dose is accumulated (considered to be 1 mg/Kg/day over four to five days). It may also be mixed with talc and used as a tracking powder, which accumulates on the animal's skin and fur, and is subsequently consumed during grooming. The use as rat poison is now declining because many rat populations have developed resistance to warfarin.

Read more at Wikipedia.org


[List your site here Free!]


Myths of Bleeding Risk Inhibit the Use of Warfarin. : An article from: Family Practice News $5.95 Coumadin necrosis may occur later: usually takes 3-10 days.(Clinical Rounds) : An article from: Skin & Allergy News $5.95
Warfarin: A Medical Dictionary, Bibliography, And Annotated Research Guide To Internet References $55.06 Aspirin Plus Warfarin May Prevent Reocclusion. : An article from: Family Practice News $5.95
Warfarin reasonable in some pregnant patients: prosthetic valves. (Rx). : An article from: Family Practice News $5.95 WARSS Results Omit Atrial Fib, Carotid Stenosis.(Warfarin-Aspiri n Recurrent Stroke Study, fibrillation) : An article from: Internal Medicine News $5.95
Prolonged, low-intensity warfarin prophylaxis prevents VTE. (Standard Regimen May Be More Effective).(venous thromboembolism) : An article from: Internal Medicine News $5.95 Legal battles rage in the marketing war over warfarin : An article from: Medical Marketing and Media $10.00
The patient's page.(side-effects of Warfarin)(methods for the treatment of Catfish stings)(complications and side-effects of antipsychotic medications ) : An article from: Southern Medical Journal $5.95 Preventing warfarin-related bleeding.(Review Article) : An article from: Southern Medical Journal $5.95

Warfarin management in pulmonary arterial hypertension is similar between bosentan, placebo, and sitaxsentan
PURPOSE: Warfarin, commonly used in pulmonary arterial hypertension (PAH) is a difficult therapy to use, requiring frequent and ongoing monitoring to ...
Warfarin use in patients with atrial fibrillation
Two percent of adults 65 to 75 years of age will develop atrial fibrillation, and the risk for developing this cardiac irregularity increases with age.
Warfarin increases mortality in intracranial arterial stenosis
Clinical Question: Is warfarin (Coumadin) better than aspirin for the treatment of patients with intracranial arterial stenosis? Setting: Outpatient ...
Choosing between warfarin and aspirin therapy for patients with atrial fibrillation
Clinical Questions What is the risk of stroke in a patient with nonvalvular atrial fibrillation, and should that patient be given warfarin (Coumadin) ...
Warfarin maintenance dosing patterns in clinical practice : implications for safer anticoagulation in the elderly population
Background: The use of anticoagulant therapy is expanding among the elderly population, in part because of the increasing prevalence of atrial fibrillation.
Effect of ginkgo and ginger on the pharmacokinetics and pharmacodynamics of warfarin in healthy subjects
Jiang X, Williams KM, Liauw WS, et al. Br J Clin Pharmacol 2005;59:425-432. AIM: The aim of this study was to investigate the effect of two common ...
Evidence-based adjustment of warfarin doses
Clinical Question What is the best way to adjust oral anticoagulation for patients taking warfarin (Coumadin)? Evidence Summary A previous Point-of-Care ...
Aspirin is far safer than Warfarin for people who have had a stroke
Stroke survivors taking the widely prescribed blood thinner warfarin (brand name: Coumadin) had more than twice the rate of death, brain hemorrhage, ...

Home Contact Resources Exchange Links ebay