Active Ingredient: Acenocoumarol
For this indication, competent medicine agencies globally authorize below treatments:
For:
Oral, between 2 milligrams acenocoumarol and 4 milligrams acenocoumarol, once daily. Afterwards, oral, between 1 milligrams acenocoumarol and 8 milligrams acenocoumarol, once daily.
Sensitivity to anticoagulants varies from patient to patient and may also fluctuate during the course of treatment. Therefore, it is essential to perform regular testing of prothrombin time (PT)/International Normalised Ratio (INR) and to adjust the patient's dosage accordingly. If this is not possible, acenocoumarol should not be used.
Acenocoumarol should be given in a single oral dose.
The dosing of acenocoumarol must be individualised. If the PT/INR value is within the normal range before starting treatment, the following dosage schedule is recommended:
The usual starting dose is between 2 mg/day to 4 mg/day without administration of a loading dose. Treatment may also be initiated with a loading dose regimen, usually 6 mg on the first day followed by 4 mg on the second day.
If the initial thromboplastin time is abnormal, treatment should be instituted with caution.
Elderly patients (≥65), patients with liver disease or severe heart failure with hepatic congestion or malnourished patients may require lower doses during treatment initiation and maintenance.
Measurement of the thromboplastin time should be carried out daily in hospital starting from second or third dose of acenocoumarol and up to the time when the coagulation status is stabilized within the target range. The interval between tests can later be extended, depending on the stability of PT/INR results. Blood samples for laboratory tests should always be taken at the same time of day.
The maintenance dose of acenocoumarol varies from patient to patient and must be checked individually on the basis of PT/INR values. PT/INR should be assessed at regular intervals, i.e. at least once a month.
The maintenance dose generally lies between 1 to 8mg daily depending on the individual patient, the underlying disease, clinical indication and desired intensity of anticoagulation.
Depending on the clinical indication, the optimal intensity of anticoagulation or therapeutic range to be aimed at generally lies between INR values of 2.0 and 3.5 (see table). Higher INR values up to 4.5 may be required in individual cases.
Recommended INR* for Oral Anti-coagulant Therapy:
| Indication | Recommended INR |
|---|---|
| Prophylaxis and treatment of venous thromboembolism (including pulmonary embolism) | 2.0–3.0 |
| Atrial fibrillation | 2.0–3.0 |
| Post-myocardial infarction (with increased risk for thromboembolic complications) | 2.0–3.0 |
| Bioprosthetic heart valves | 2.0–3.0 |
| Secondary prophylaxis in patients wth antiphospholipid syndrome | 2.0–3.0 |
| Antiphospholipid syndrome patients with venous thromboembolism on therapeutic vitamin K antagonist | 2.0–3.5 |
| Mechanical heart valves | 2.0–3.5 |
* The PT, which reflects the reduction of Vitamin K dependent clotting factors VII, X and II, is dependent on the responsiveness of the thrombosplastin used for PT-testing. The responsiveness of the respective local thromboplastin compared to World Health Organisation international reference preparations is reflected by its International Sensitivity Index (ISI).
The "International Normalised Ratio" (INR) was introduced for the purpose of standardisation of the PT. The INR is the ratio of the patient's anticoagulated plasma PT to the normal plasma PT using the same thromboplastin in the same test system raised to the power of a value defined by the International Sensitivity Index.
Generally, after withdrawal of acenocoumarol, there is usually no danger of reactive hypercoagulability and therefore it is not necessary to give gradually diminishing doses. However, in extremely rare cases, in some high risk patients (e.g. after myocardial infarction), withdrawal should be gradual.
The anticoagulant effect of acenocoumarol persists beyond 24 hours. If the patient forgets to take the prescribed dose of acenocoumarol at the scheduled time, the dose should be taken as soon as possible on the same day. The patient should not double the daily dose to make up for a missed dose, but should refer back to his or her doctor.
In clinical situations which require rapid anticoagulation, initial treatment with heparin is preferred since the anticoagulant effect of acenocoumarol is delayed. Conversion to acenocoumarol may begin concomitantly with heparin therapy or may be delayed depending on the clinical situation. To ensure continuous anticoagulation, it is advisable to continue to prescribe full dose heparin therapy for at least 4 days after initiation of acenocoumarol and to continue heparin therapy until the INR has been in the target range on at least two consecutive days. During the transition phase close monitoring of anticoagulation is necessary.
Patients on acenocoumarol, who undergo surgical or invasive procedures require close surveillance of their coagulation status. Under certain conditions, e.g. when the operation site is limited and accessible to permit effective use of local procedures for haemostasis, dental and minor surgical procedures may be performed during continued anticoagulation, without undue risk of haemorrhage. The decision to discontinue acenocoumarol, even for a short period of time, should carefully consider individual risks and benefits. The introduction of bridging anticoagulant treatment, e.g. with heparin should be based on careful assessment of the expected risks of thromboembolism and bleeding.
A dose lower than the recommended adult dose may be sufficient in elderly patients. Caution and more frequent monitoring of PT/INR is recommended.
The daily dosage should always be taken at the same time of day.
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