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

The effect of lyophilization on the physical characteristics of two different molecular mass hyaluronates (164 and 741 kDa) has been evaluated using dynamic oscillatory viscometry and size exclusion chromatography. The hyaluronates were prepared as either the free acid or the sodium 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 of the hyaluronates in the free acid form. Size exclusion chromatography indicated a reduction in molecular mass of these samples. These data indicate that lyophilization of hyaluronates as the free acid, as opposed to a sodium salt form, can have a detrimental effect on their physical characteristics.