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Acenocoumarol tablets 1mg

Updated 2 Feb 2023 | Vitamin K antagonists


Oral formulations of acenocoumarol

Drugs List

  • acenocoumarol 1mg tablets
  • SINTHROME 1mg tablets
  • Therapeutic Indications


    Thromboembolic disorders - prophylaxis and treatment


    Regular coagulation tests, prothrombin time (PT) or International Normalised Ration (INR), should be performed to determine the patient's sensitivity to the anticoagulant therapy. Adjust dosage according to response.

    Give as a single oral dose at the same time each day.


    If initial thromboplastin time is abnormal, only institute treatment with caution.
    If the PT/INR value is within the normal range before starting treatment, the following dosage schedule is recommended:

    Initial dose
    The usual starting dose is between 2 mg daily to 4 mg daily 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.

    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 the day.

    Maintenance therapy
    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 8 mg daily depending on the individual patient, underlying disease, clinical indication and the 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 vales of 2.0 and 3.5. Higher INR values up to 4.5 may be required in individual cases.


    A dose lower than the recommended adult dose may be sufficient.

    More frequent monitoring of prothrombin time and INR is recommended.

    Additional Dosage Information

    Recommended INR for oral anti-coagulation therapy
    Prophylaxis and treatment of venous thromboembolism (Including pulmonary embolism): 2.0 to 3.0
    Atrial fibrillation: 2.0 to 3.0
    Post-myocardial infarction (with increased risk for thromboembolic complications): 2.0 to 3.0
    Bioprosthetic heart valves: 2.0 to 3.0
    Secondary prophylaxis in patients with antiphospholipid syndrome: 2.0 to 3.0
    Antiphospholipid syndrome patients with venous thromboembolism on therapeutic vitamin K antagonist: 2.0 to 3.5
    Mechanical heart valves: 2.0 to 3.5

    Missed doses
    The anticoagulant effect of acenocoumarol persists beyond 24 hours. if the patients 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 take the missed dose by doubling the daily dose to make up for missed doses, but should refer back to their doctor.

    Conversion from heparin therapy
    Patients who 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 INR has been in the target range on at least two consecutive days. During the transition phase close monitoring of anticoagulation is necessary.

    Treatment during dentistry and surgery
    Patients on acenocoumarol, who undergo surgical or invasive procedures require close supervision 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.


    Children under 18 years
    Haemorrhagic diathesis
    Major surgery
    Patients unable to co-operate
    Predisposition to haemorrhage
    Raised fibrinolytic activity post operatively
    Acute pericarditis
    Central nervous system surgery
    Haematological disorder
    Infective endocarditis
    Ocular surgery
    Peptic ulcer
    Pericardial effusion
    Severe hepatic impairment
    Severe hypertension
    Severe renal impairment

    Precautions and Warnings

    Acute infection
    Acute inflammatory conditions
    Females of childbearing potential
    Glucose-galactose malabsorption syndrome
    Hepatic impairment
    Lactose intolerance
    Malabsorption syndrome
    Myocardial infarction
    Neoplasm with increased bleeding risk
    Protein C deficiency disease
    Protein S deficiency disease
    Recent ischaemic cerebrovascular accident
    Renal impairment
    Severe cardiac failure

    Contains lactose
    Avoid concurrent intramuscular injections - risk of haematoma
    Caution if procedures requiring shortened thromboplastin time are needed
    Monitor prothrombin times
    Withdraw gradually in patients at risk of reactive hypercoagulability
    Advise patient not to take NSAIDs unless advised by clinician
    Advise patient not to take St John's wort concurrently
    Advise patient to moderate alcohol intake during treatment
    Advise patient to avoid large quantities of cranberry juice
    Female: Ensure adequate contraception during treatment

    Gastro-intestinal absorption disorders may alter the anticoagulant activity of acenocoumarol.

    Malnourished patients, patients with liver disease and severe heart failure with hepatic congestion may require lower doses during treatment initiation and maintenance.

    In elderly patients use with caution, with lower doses during treatment initiation and maintenance and more frequent monitoring of prothrombin time and INR is recommended.

    Pregnancy and Lactation


    Acenocoumarol is contraindicated in pregnancy.

    The use of acenocoumarol during the first trimester carries significant risk to the foetus. Exposure in the 6th to 9th weeks of gestation may produce a pattern of defects termed the 'foetal warfarin syndrome'. Infants exposed before this period have had other congenital anomalies. Spontaneous abortions, still births, and neonatal deaths (Briggs, 2011).

    The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14 to 17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( ) or if this is unavailable at the backup site ( ).


    Use acenocoumarol with caution in breastfeeding.

    Acenocoumarol passes into breast milk in small quantities but should not harm the infant. The infant should be given vitamin K as a prophylactic measure.

    Coagulation tests and vitamin K status evaluation of the infant should be undertaken before advising women to breastfeed. Careful monitoring of the mother is required to ensure that the recommended PT/INR values are not exceeded.

    Acenocoumarol therapy during breastfeeding poses little risk to the breastfed infant.

    Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
    Specialist advice is available from the UK Drugs in Lactation Advisory Service at

    Side Effects

    "Purple toes" syndrome
    Alopecia (transient)
    Decreased appetite
    Gastro-intestinal disturbances
    Hypersensitivity reactions
    Liver damage
    Skin necrosis


    It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.

    The following number will direct the caller to the relevant local centre (0844) 892 0111

    Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( ) or if this is unavailable at the backup site ( ).

    Further Information

    Last Full Review Date: July 2014

    Reference Sources

    Drugs During Pregnancy and Lactation: Treatment Options and Risk Assessment, 2nd edition (2007) ed. Schaefer, C., Peters, P. and Miller, R. Elsevier, London.

    Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk, 9th edition (2011) ed. Briggs, G., Freeman, R. and Yaffe, S. Lippincott Williams & Wilkins, Philadelphia.

    Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press Accessed on July 7, 2014.

    Martindale: The Complete Drug Reference, 37th edition (2011) ed. Sweetman, S. Pharmaceutical Press, London.

    Summary of Product Characteristics: Sinthrome Tablets 1mg. Alliance Pharmaceuticals Ltd. Revised May 2014.

    US National Library of Medicine. Toxicology Data Network. Drugs and Lactation Database (LactMed).
    Available at:
    Acenocoumarol Last revised: July 9, 2014
    Last accessed: July 9, 2014

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