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WARFARIN is a brand name for Warfarin. The medicine, its uses, side effects and dosage are the same regardless of brand.
Used for: Acute venous thrombosis and pulmonary embolism (initially together with heparin or low molecular weight heparin). Ventrothromboprophylaxis. Acquired heart disease with particular embolic risk, e.g. chronic atrial fibrillation, cardiomyopathy and large transmural myocardial infarction. Elective electrical…
Verbatim from this product's MHRA label. Tap a section to expand.
Posology Adults Initial dosage Day 1: 5-10 mg warfarin, depending on the patient’s genetic make-up, weight, age and general health, etc. (see below). 5 mg warfarin.
Day 3:
Preliminary maintenance dose, based on the effect of the initial dose on INR (International Normalised Ratio) on day 3. A high initial dosage can result in excessive anticoagulation or, alternatively, hypercoagulation during the adjustment phase because of an imbalance between pro and anticoagulation factors.
g. 5 mg warfarin per day) and to first check the INR value on days 3-4. 25 mg to 25 mg warfarin daily in some patients. The entire daily dose should be taken at one time. Effective prevention of thrombosis is generally only achieved after 5 days of treatment at the earliest, provided the INR value has reached the recommended therapeutic level.
Managing anticoagulation treatment A coagulation test should be done before the start of treatment. 0. Warfarin has a narrow therapeutic window and sensitivity to warfarin varies from person to person and even within the same person.
Therefore treatment intensity should be checked on a regular basis. 2). 5). INR values are checked every day to every other day during the first week and subsequently once or twice a week until the patient is on the maintenance dose. Once a stable level is achieved, the interval between checks can often be extended to 4-6 weeks or sometimes longer periods.
5). 5), is recommended. 5 may be recommended, depending on the type of prosthesis. For patients with a particularly high bleeding risk and for those who are unable to cope with a normal intensity due to age or other reason, a lower intensity may be considered, even if this can be associated with a weaker effect.
It should be pointed out that the above therapeutic areas are only general outlines and should be modified depending on the condition being treated, the degree of relative contraindications, local treatment guidelines, and the patient’s ability to co-operate.
Due to local or regional treatment recommendations and different analytical methods, there may be variations in therapeutic INR. The recommended INR value can vary in other countries due to different analytical methods. Before any foreign travel, the patient should be informed that warfarin tablets of many different strengths can be found abroad.
Treatment with warfarin can cause bleeding, in some cases serious, from any organ, including epistaxis, haemoptysis, haematuria, gingival bleeding, haematomas, vaginal bleeding, subconjunctival haemorrhage, gastrointestinal haemorrhage, cerebral haemorrhage and prolonged and extensive bleeding following surgery or trauma.
Bleeding that results in death, hospitalisation or a transfusion requirement has been reported among patients on long-term anticoagulant treatment. Independent risk factors for major haemorrhage during anticoagulant treatment with warfarin are: • advanced age • treatment intensity • previous cerebral haemorrhage • previous gastrointestinal haemorrhage.
2), which cause increased sensitivity to warfarin, are at increased risk of an excessive anticoagulant effect during warfarin treatment, which can increase the risk of bleeding complications. Haemoglobin levels and INR should be closely monitored.
4) Not known Investigations Unexplained drop in haematocrit; haemoglobin decreased Not known Reporting of suspected adverse reactions: Reporting suspected adverse reactions after authorisation of the medicinal product is important.
It allows continued monitoring of the benefit/risk balance of the medicinal product. uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.
It is important to assess the patient’s ability to follow given treatment instructions. Patients with drug abuse such as alcoholism, or patients suffering from depression or dementia, may have difficulty following the stated dosage regimen.
The risk of drug interactions leading to altered treatment effect of Waran is high. 5) Patients should be given a patient-held information booklet (“warfarin card”) and informed of symptoms for which they should seek medical attention.
Start of therapy Anticoagulant-related nephropathy In patients with altered glomerular integrity or with a history of kidney disease, acute kidney injury may occur, possibly in relation to episodes of excessive anticoagulation and hematuria.
A few cases have been reported in patients with no pre-existing kidney disease. Close monitoring including renal function evaluation is advised in patients with a supratherapeutic INR and hematuria (including microscopic) Monitoring When warfarin is started using a standard dosing regimen the INR should be determined daily or on alternate days in the early days of treatment.
Once the INR has stabilised in the target range the INR can be determined at longer intervals. g. patients with severe hypertension, liver or renal disease. Patients for whom adherence may be difficult should be monitored more frequently.
Thrombophilia Patients with protein C deficiency are at risk of developing skin necrosis when starting warfarin treatment. In patients with protein C deficiency, therapy should be introduced without a loading dose of warfarin even if heparin is given.
Patients with protein S deficiency may also be at risk and it is advisable to introduce warfarin therapy slowly in these circumstances. Risk of haemorrhage The most frequently reported adverse effect of all oral anticoagulants is haemorrhage.
1. 4 for further details). • Clinically significant bleeding. 4). • Within 48 hours postpartum. 6). • Use of products containing St. 5). 2). • Patients at high risk of bleeding, for example: − patients with bleeding disorders − bleeding tendency gastrointestinal, urogenital or respiratory − oesophageal varices − arterial aneurysm − spinal puncture − peptic ulcer disease − serious wounds (including surgical wounds) − bacterial endocarditis − malignant hypertension
Not medical advice. Always read the patient information leaflet and follow your prescriber or pharmacist.
Other brands of Warfarin in United Kingdom.
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Combination with heparin In acute cases, it is recommended that warfarin be combined with heparin to ensure a rapid anticoagulant effect. Special patient groups Paediatric population Data on the use of warfarin in children is limited.
1 mg/kg for children with impaired hepatic function. The dose is then adjusted to a similar target INR to that for adults. 2). Treatment with warfarin is not recommended for newborns on account of the risk of simultaneous vitamin K deficiency.
The therapeutic INR for younger children is not fully known. 5). Treatment of children, and especially small children, requires specialist knowledge. Elderly Elderly patients require lower doses than younger adults. 5 mg, which is then adjusted based on INR.
It is not known what the reduced dose requirement is due to, but it is likely that there is a combination of pharmacokinetic and pharmacodynamic changes. Impaired hepatic function Impaired hepatic function can enhance the effect of warfarin through inhibited synthesis of clotting factors and reduced metabolism of warfarin.
2). A reduction of the initial dose should be considered. 3). 2), clinical practice shows that patients with impaired renal function require lower warfarin doses, have poorer coagulation control and have a higher risk of severe bleeding.
4). Patients with genetically abnormal enzyme types A markedly abnormal INR response may be due to genetic factors, […]
g. concomitant NSAID use, recent ischaemic stroke, bacterial endocarditis, previous gastrointestinal bleeding). 5). All patients treated with warfarin should have INR monitored regularly. Those at high risk of bleeding may benefit from more frequent INR monitoring, careful dose adjustment to desired INR, and a shorter duration of therapy.
Patients should be instructed on measures to minimise risk of bleeding and to report immediately to physicians signs and symptoms of bleeding. Checking the INR and reducing or omitting doses depending on INR level is essential, following consultation with anitcoagulation services if necessary.
If the INR is found to be too high, reduce dose or stop warfarin treatment; sometimes it will be necessary to reverse anticoagulation. INR should be checked within 2-3 days to ensure that it is falling. Any concomitant anti-platelet drugs should be used with caution due to an increased risk of bleeding.
Haemorrhage Haemorrhage can indicate an overdose of warfarin has been taken. 9. Unexpected bleeding at therapeutic levels should always be investigated and INR monitored. Ischaemic stroke Anticoagulation following an ischaemic stroke increases the risk of secondary haemorrhage into the infarcted brain.
In patients with atrial fibrillation long term treatment with warfarin is beneficial, but the risk of early recurrent embolism is low and therefore a break in treatment after ischaemic stroke is justified. Warfarin treatment should be re-started 2-14 days following ischaemic stroke, depending on the size of the infarct and blood pressure.
In patients with large embolic strokes, or uncontrolled hypertension, warfarin treatment should be stopped for 14 days. Surgery including dental surgery. 2). In the cases of major surgery and organ punctures, an individually adapted programme for warfarin treatment should be developed.
For surgery where there is a risk of severe bleeding, warfarin should be stopped 3 days prior to surgery. g. 5 and heparin therapy should be started. If surgery is required and warfarin cannot be stopped 3 days beforehand, anticoagulation should be reversed with low-dose vitamin K.
The timing for re-instating warfarin therapy depends on the risk of post-operative haemorrhage. In most instances warfarin treatment can be re-started as soon as the patient has an oral intake. Active peptic ulceration Due to a high risk of bleeding, patients with active peptic ulcers should be treated with caution.
Such patients should be reviewed regularly and informed of how to recognise bleeding and what to do in the event of bleeding occurring. 5). Any change to medication, including self-medication with OTC products, warrants increased monitoring of the INR.
Patients should be instructed to inform their doctor before they start to take any additional medications including over the counter medicines, herbal remedies or vitamin preparations. Thyroid disorders The rate of […]