EFFECT OF LYOPHILIZATION ON THE PHYSICAL CHARACTERISTICS OF MEDIUM MOLECULAR-MASS HYALURONATES

The effect of lyophilization on the physical characteristics of two di fferent molecular mass hyaluronates (164 and 741 kDa) has been evaluat ed using dynamic oscillatory viscometry and size exclusion chromatogra phy. The hyaluronates were prepared as either the free acid or the sod ium salt. The rheological and SEC profiles of sodium hyaluronate were not affected by lyophilization. In contrast, the complex viscosity and related dynamic moduli were markedly decreased after lyophilization o f the hyaluronates in the free acid form. Size exclusion chromatograph y indicated a reduction in molecular mass of these samples. These data indicate that lyophilization of hyaluronates as the free acid, as opp osed to a sodium salt form, can have a detrimental effect on their phy sical characteristics.