MEDICINAL CHEMISTRY

Heparin for therapeutic use is obtained from lung of ox or intestinal mucosa of ox, pigs or
sheep. During the process of isolation the glucosaminoglycan chains become degraded to
give a heterogeneous mixture of fragments with molecular weights ranging from 5,000 to
30,000 daltons. Low molecular weight heparins (less than 7,000 daltons) are fragments
of heparin with anticoagulant activity. These are isolated from standard heparin by gel
filtration chromatography or differential precipitation with ethanol.
Heparinoids are the compounds that have structural analogy to heparins. They are
sulphuric acid esters of various polysaccharides. The heparinoids are in some respects
more active than heparin in animals. Dextrans which are linear glucose polymers
produced by Leuconostoc mesenteroides have been used as the sulphates as
antithrombotic agents.
Heparin acts by increasing the rate of the thrombin-antithrombin reaction by serving as a
catalytic template to which both the inhibitor and the protease get attached. Thus heparin
exerts its anticoagulant effect by inhibiting the activity of thrombin. Other factors such as
Xa are also inhibited. Heparin in high doses can also interfere with platelet aggregation
which may prolong bleeding time. Heparin is used as heparin sodium and heparin
calcium.
Official Drugs
Heparin Sodium, B.P., I. P.: Heparin sodium is a preparation containing the sodium salt
of heparin. It is a white or greyish-white, moderately hygroscopic powder. It is freely
soluble in water. Solutions are sterilized by filtration. It is stored in tightly-closed
containers, sealed so as to exclude microorganisms, and kept in dry place. If the contents
are intended to be used for the manufacture of injection, the container should be sterile
and temper-evident. The source of the material should be stated on the label.
Heparin is not absorbed from the gastrointestinal tract. Following parenteral
administration it is extensively bound to plasma proteins. It does not cross placenta or
appear in the milk of nursing mother. Heparin inhibits clotting of blood both in vivo and
in vitro. Heparin is used in the treatment and prophylaxis of deep-vein thrombosis and
pulmonary embolism as well as arterial thromboembolism. It is also used as an
anticoagulant during haemodialysis, blood transfusion and collection.
Heparin sodium is given in doses of 20,000 to 50,000 Units daily by intravenous injection
for the treatment. For prophylaxis it is given by subcutaneous injection, 10,000 to 15,000
Units daily, in divided doses.
Preparation: Heparin Sodium Injection, I.P. (Heparin Injection, B.P.); Proprietary
Names: Liquaemin Sodium; Monoparin
Heparin Calcium, B.P.: It is a preparation containing the calcium salt of heparin. It is a
white or almost white, moderately hygroscopic powder. It is freely soluble in water. Its
conditions of storage, other requirements, actions and uses are similar to those of heparin
sodium.
Preparation: Heparin Injection, B.P; Proprietary Names: Calciparine; Monoparin
calcium