Mixtures of polysaccharides derived from heparin, their preparation and pharmaceutical compositions containing them

Abstract

The present invention relates to mixtures of polysaccharides derived from heparin having a mean molecular weight of 1500 to 3000 Daltons and an anti-Xa/anti-IIa ratio greater than 30, their method of preparation and pharmaceutical compositions containing them.

1 - 53 . (canceled) 
     
     
         54 . A mixture of sulfated oligosaccharides having the following characteristics:
 a mean molecular weight of from about 1500 daltons to about 3000 daltons,   an anti-Xa activity of between 150.5 IU/mg and 200 IU/mg,   an anti-IIa activity of less than about 10 IU/mg, and   an anti-Xa activity/anti-IIa activity ratio of greater than about 30;   wherein the constituent oligosaccharides of the mixture:
 contain 2 to 26 saccharide units, 
 have a 4,5-unsaturated uronic acid 2-0-sulfate unit at one of their ends, 
 contain a hexasaccharide fraction, wherein from about 8% to about 15% of the hexasaccharide fraction of the mixture is the hexasaccharide ΔIIa-II s -Is of formula: 
   
       
         
           
           
               
               
           
         
         
           and are in the form of at least one salt chosen from alkali and alkaline earth metal salts. 
         
       
     
     
         55 . The mixture of  claim 54 , wherein the alkali or alkaline-earth metal salt is selected from sodium, potassium, calcium and magnesium salts. 
     
     
         56 . The mixture of  claim 54 , wherein the mixture exhibits an anti-IIa activity of less than 5 IU/mg. 
     
     
         57 . The mixture of  claim 54 , wherein the mixture exhibits an anti-IIa activity of from about 0.5 IU/mg to about 3.5 IU/mg. 
     
     
         58 . The mixture of  claim 54 , wherein the mixture exhibits an anti-Xa activity/anti-IIa activity ratio of greater than about 50. 
     
     
         59 . The mixture of  claim 54 , wherein the mixture exhibits an anti-Xa activity/anti-IIa activity ratio of greater than about 100. 
     
     
         60 . The mixture of  claim 54 , wherein the mixture has a mean molecular weight of between 2000 and 3000 Daltons. 
     
     
         61 . The mixture of  claim 54 , wherein the mixture has a mean molecular weight of between 2400 and 2650 Daltons. 
     
     
         62 . The mixture of  claim 54 , wherein the mixture exhibits an anti-Xa activity of between 150.5 and 200 IU/mg, an anti-IIa activity of between 0.5 and 3.5 IU/mg, and a mean molecular weight of between 2400 and 2650 Daltons. 
     
     
         63 . The mixture of  claim 54 , wherein the hexasaccharide fraction represents from about 15% to about 25% of the mixture of oligosaccharides. 
     
     
         64 . The mixture of  claim 54 , wherein the mixture is prepared by a process comprising:
 depolymerising a quaternary ammonium salt of a benzyl ester of heparin in a reaction medium comprising an organic solvent and an organic base with a pKa greater than 20, wherein the organic base is selected from phosphazenes, wherein the base:ester molar ratio is from 0.6 to 2, controlling the water content of the reaction medium to be 0.2% or less by measuring the water content and determining whether adjustment is necessary;   wherein the depolymerization and/or water control steps are performed under conditions such that a mixture of sulfated oligosaccharides having an anti-Xa activity of between 150.5 IU/mg and 200 IU/mg is produced.   
     
     
         65 . The mixture of  claim 64 , wherein the organic base with a pKa greater than 20 is 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,2,3-diazaphosphorine. 
     
     
         66 . The mixture of  claim 64 , wherein the organic solvent is dichloromethane. 
     
     
         67 . The mixture of  claim 64 , wherein said quaternary ammonium salt of the benzyl ester of heparin is the benzethonium, cetylpyridinium or cetyltrimethylammonium salt. 
     
     
         68 . A pharmaceutical composition comprising the mixture of  claim 54  and an inert excipient. 
     
     
         69 . A method for the treatment of at least one condition selected from venous thrombosis, arterial thrombosis, deep vein thrombosis, pulmonary embolism, unstable angina, myocardial infarction, and cardiac ischemia, the method comprising administering to a patient in need thereof a pharmaceutical composition comprising an effective amount of the mixture of  claim 54 .