Product Details

NICOUMALONE

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.

Associated Conditions

• Coronary Occlusions
• Pulmonary Embolism (PE)
• Systemic Embolism
• Thrombosis, Venous
• Transient Ischaemic Attack (TIA)

Pharmacodynamics

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.

Mechanism of action

Acenocoumarol inhibits vitamin K reductase, resulting in depletion of the reduced form of vitamin K (vitamin KH2). As vitamin K is a cofactor for the carboxylation of glutamate residues on the N-terminal regions of vitamin K-dependent clotting factors, this limits the gamma-carboxylation and subsequent activation of the vitamin K-dependent coagulant proteins. The synthesis of vitamin K-dependent coagulation factors II, VII, IX, and X and anticoagulant proteins C and S is inhibited resulting in decreased prothrombin levels and a decrease in the amount of thrombin generated and bound to fibrin. This reduces the thrombogenicity of clots.

Absorption

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

Volume of 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

Protein binding

98.7% protein bound, mainly to albumin

Metabolism

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.

• Acenocoumarol
   
  6-Hydroxy-R-acenocoumarol
• Acenocoumarol
   
  7-Hydroxy-R-acenocoumarol
• Acenocoumarol
   
  8-Hydroxy-R-acenocoumarol

Route of elimination

Mostly via the kidney as metabolites.

SOURCE:DRUGBANK