DRUGS THAT REDUCE THE COAGULABILITY (ABILITY TO COAGULATE) OF BLOOD A nticoagulants
Muco polysaccharide found in the mast cells of liver, intestine and lungs. Strongest acid in the body It is a powerful anticoagulant that acts instantaneously both in vivo and in vitro. HEPARIN
M echanism of action Heparin activates Anti thrombin III which inhibits activated thrombin and coagulation factors.
Not effective orally. When given Intra muscularly it may cause hematomas. It is normally given IV or SC. Heparin is metabolised by heparinase in the liver. P harmacokinetics
Includes enoxaparin , dalteparin , reviparin , nadreparin etc. LMWH has a relatively favorable pharmacokinetic profile. Inhibits only factor Xa and has a weak effect on thrombin. Thus, aPTT or clotting time are not prolonged. Lower risk of osteoporosis. Lower risk of thrombocytopenia and thrombosis. L ow molecular weight heparin (LMWH)
In severe heparin overdose an antagonist may be needed to arrest its anti coagulant effects. Protamine sulphate is the commonly used heparin antagonist. Given IV, it neutralises heparin. In the absence of heparin, protamine sulphate can act as a weak anticoagulant itself. Fondaxaparinux is used for the prevention and treatment of deep vein thrombosis and pulmonary embolism. H eparin antagonists
Heparan sulphate present in some tissues is similar to heparin. Danaparoid is a mixture of heparinoids and acts by inhibiting factor Xa . It is longer acting. H eparinoids