Patent ID: 8003623

Claim:
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 161 IU/mg and 192 IU/mg, an anti-IIa activity of less than about 10 IU/mg, and an anti-Xa activity/anti-lla 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-IIs-Is of formula: and are in the form of at least one salt chosen from alkali and alkaline earth metal salts; 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 161 IU/mg and 192 IU/mg is produced.