Molecule

Drug Groups

approved

Description

Acenocoumarol is a coumarin derivative used as an anticoagulant. Coumarin derivatives inhibit the reduction of vitamin K by vitamin K reductase. This prevents carboxylation of vitamin K-dependent clotting factors, II, VII, XI and X, and interferes with coagulation. Hematocrit, hemoglobin, international normalized ratio and liver panel should be monitored. Patients on acenocoumarol are prohibited from giving blood.

Indication

For the treatment and prevention of thromboembolic diseases. More specifically, it is indicated for the for the prevention of cerebral embolism, deep vein thrombosis, pulmonary embolism, thromboembolism in infarction and transient ischemic attacks. It is used for the treatment of deep vein thrombosis and myocardial infarction.

Pharmacology

Acenocoumarol inhibits the reduction of vitamin K by vitamin K reductase. This prevents carboxylation of certain glutamic acid residues near the N-terminals of clotting factors II, VII, IX and X, the vitamin K-dependent clotting factors. Glutamic acid carboxylation is important for the interaction between these clotting factors and calcium. Without this interaction, clotting cannot occur. Both the extrinsic (via factors VII, X and II) and intrinsic (via factors IX, X and II) are affected by acenocoumarol.

Toxicity

The onset and severity of the symptoms are dependent on the individual's sensitivity to oral anticoagulants, the severity of the overdosage, and the duration of treatment. Bleeding is the major sign of toxicity with oral anticoagulant drugs. The most frequent symptoms observed are: cutaneous bleeding (80%), haematuria (with renal colic) (52%), haematomas, gastrointestinal bleeding, haematemesis, uterine bleeding, epistaxis, gingival bleeding and bleeding into the joints. Further symptoms include tachycardia, hypotension, peripheral circulatory disorders due to loss of blood, nausea, vomiting, diarrhoea and abdominal pains.

Affected Organisms

Biotransformation

Extensively metabolized in the liver via oxidation forming two hydroxy metabolites and keto reduction producing two alcohol metabolites. Reduction of the nitro group produces an amino metabolite which is further transformed to an acetoamido metabolite. Metabolites do not appear to be pharmacologically active.

Absorption

Rapidly absorbed orally with greater than 60% bioavailability. Peak plasma levels are attained 1 to 3 hours following oral administration.

Half Life

8 to 11 hours.

Protein Binding

98.7% protein bound, mainly to albumin

Elimination

Mostly via the kidney as metabolites

Distribution

The volume of distribution at steady-state appeared to be significantly dose dependent: 78 ml/kg for doses < or = 20 microg/kg and 88 ml/kg for doses > 20 microg/kg respectively

References

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