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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: Warfarin is indicated for the prophylaxis of systemic embolisation in patients with rheumatic heart disease and atrial fibrillation. Warfarin is indicated for the prophylaxis after insertion of prosthetic heart valves. Warfarin is indicated for the prophylaxis and treatment of venous thrombosis and pulmonary embolism.…
Verbatim from this product's MHRA label. Tap a section to expand.
Posology Adults and elderly patients:
The typical induction dose of warfarin is 10 mg daily for 2 days, but this should be tailored to individual requirements. Baseline prothrombin measurements (PT) should be taken before beginning therapy with warfarin. The daily maintenance dose of warfarin is usually 3 to 9 mg taken at the same time each day.
The exact maintenance dose for an individual is dependent on the prothrombin time or other appropriate coagulation tests. The maintenance dose is omitted if the prothrombin time is excessively prolonged. Once the maintenance dose is stabilised in the therapeutic range, it is rarely necessary to alter it.
In emergencies, anticoagulant therapy should be initiated with heparin and warfarin together. Where there is less urgency, as in patients disposed to or at special risk of thromboembolism, anticoagulant therapy may be initiated with warfarin alone.
Concomitant heparin therapy affects the results of control tests and should be discontinued at least six hours before the first test is carried out. Control is established with INR monitoring at regular intervals and subsequent warfarin maintenance dosage further adjusted according to the results obtained.
Paediatric population:
No data are available. Method of administration Warfarin Tablets are for oral use
MedDRA system organ class Adverse Reaction Infections and infestations Fever Immune system disorders Hypersensitivity Nervous system disorders Cerebral haemorrhage; Cerebral subdural haematoma Vascular disorders Haemorrhage Respiratory, thoracic and mediastinal disorders Haemothorax, epistaxis Gastrointestinal disorders Gastroinestinal haemorrhage, rectal haemorrhage, haematemesis; pancreatitis; diarrhoea; nausea; vomiting; melaena Hepatobiliary disorders Jaundice; hepatic dysfunction Skin and subcutaneous disorders Rash; alopecia; purpura; ‘purple toes’ syndrome; erythematous swollen skin patches leading to ecchymosis, infarction and skin necrosis; calciphylaxis Renal and Urinary disorders Haematuria; anticoagulant-related nephropathy Investigations Unexplained drop in haematocrit; haemoglobin decreased 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
Most adverse events reported with warfarin are a result of over anticoagulation therefore it is important that the need for therapy is reviewed on a regular basis and therapy discontinued when no longer required. Patients should be given a patient-held information booklet (‘warfarin card’) and informed of symptoms for which they should seek medical attention.
Commencement of therapy 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 stabilized 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. 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 minimize 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 anticoagulation 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.
4) - Within 48 hours postpartum. 6). 5)
Not medical advice. Always read the patient information leaflet and follow your prescriber or pharmacist.
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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 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.
5. 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. g. tooth extraction. 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. Calciphylaxis Calciphylaxis is a rare syndrome of vascular calcification with cutaneous necrosis, associated with high mortality.
The condition is mainly observed in patients with end- stage renal disease on dialysis or in patients with known risk factors such as protein C or S deficiency, hyperphosphataemia, hypercalcaemia or hypoalbuminaemia. Rare cases of calciphylaxis have been reported in patients taking warfarin, also in the absence of renal disease.
In case calciphylaxis is diagnosed, appropriate treatment should be started and consideration should be given to stopping treatment with warfarin. 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 […]