Structural and activity variability of fractions with different charge density and chain length from pharmaceutical heparins.

Heparin is a structurally complex polysaccharide used as a clinical anticoagulant. It is comprised of a heterogeneous mixture of polysaccharide chains having a variety of sequences and lengths. The production methods and regulatory controls of pharmaceutical heparins have changed over the years. This study assesses the structural and activity uniformity of the polysaccharide chains comprising two contemporary heparin products. The heparin fractions with different sizes and charges were separated with size exclusion and ion exchange chromatography. The fractions were analyzed for their molecular weight properties, di- and tetrasaccharide compositions, and anti-factor IIa and anti-factor-Xa activities. The distribution of these properties through chains of different lengths and ones with different charge density were compared. The results demonstrate that with the increase in heparin purity, activity and molecular weight required by the current pharmacopeia, the uniformity of pharmaceutical heparin products have increased.