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MAREVAN is a brand name for Warfarin. The medicine, its uses, side effects and dosage are the same regardless of brand.
Used for: Prophylaxis of systemic embolism in patients with rheumatic heart disease and atrial fibrillation. Prophylaxis after insertion of prosthetic heart valves. Prophylaxis and treatment of venous thrombosis and pulmonary embolism. Transient attacks of cerebral ischaemia.
Verbatim from this product's MHRA label. Tap a section to expand.
Posology Adults:
The typical induction dose is 10mg daily for 2 days but this should be tailored to individual requirements. The daily maintenance dose is usually 3 to 9mg taken at the same time each day. The exact maintenance dose depends on the prothrombin time or other appropriate coagulation tests.
Control tests should be made at regular intervals and the maintenance dose should be adjusted according to the results obtained. Once the maintenance dose is established, it is rarely necessary to alter it. In emergencies, anticoagulant therapy should be initiated with heparin and warfarin together.
Concomitant therapy with heparin affects the results of control tests, and should be discontinued at least six hours before the first test is carried out.
Elderly:
As for adults, but dosage may need to be lowered.
Paediatric population:
No data are available. Method of administration Oral.
The following adverse reactions are classified by system organ class and ranked under heading of frequency using the following convention: very common (≥1/10); common (≥1/100 to <1/10); uncommon (≥1/1,000 to <1/100); rare (≥1/10,000 to <1/1,000); very rare (<1/10,000) and not known – cannot be estimated from the available data.
4), haematuria Investigations Not known Unexplained drop in haematocrit; haemoglobin decreased Pruritic lesions (macular, papular, vesicular and urticarial) have also been reported. Skin necrosis is a rare but potentially serious effect.
It is associated with loading doses of over 10mg, and occurs mainly in obese elderly women, usually within 3 - 5 days of starting treatment. Leukocytoclastic vasculitis, a primarily cutaneous small vessel vasculitis possibly with systemic involvement may be encountered.
It may be associated with a Protein C or Protein S deficiency. It usually affects fatty tissues (breast, thighs, buttocks) and starts as a localised, painful, erythematous or haemorrhagic lesion which becomes bullous and eventually necrotic.
Advice on management usually includes discontinuing the warfarin.
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.
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. 5). 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 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. g. 3). 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 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. 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.
1. 4).
Not medical advice. Always read the patient information leaflet and follow your prescriber or pharmacist.
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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. 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. 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. Dental Surgery Warfarin need not be stopped before routine dental surgery, eg, 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. Thyroid disorders The rate of warfarin metabolism depends on thyroid status.
Therefore patients with hyper- or hypo-thyroidism should be closely monitored on starting […]