Elucidation of the time-dependent degradation process in insoluble hyaluronic acid formulations with a controlled degradation rate.

Degradation rate of hyaluronic acid to prolong its stability in vivo would be beneficial. We investigated a potential solution for prolonging the stability of hyaluronic acid within the body. We focused on decreasing the swelling ratio to slow the degradation rate of hyaluronic acid by insolubilizing sodium hyaluronate without using potentially harmful substances such as crosslinkers or modifiers. Hyaluronic acid formulations were created with three different swelling ratios and time-dependent morphological changes in hyaluronic acid formulations and were scored based on each swelling ratio. In vivo degradation was modeled in simulated body fluid and the extent of decay of test membranes were monitored over time. Results showed that, by adjusting the swelling ratio, the degradation rate of hyaluronic acid formulation could be controlled. Our research could lead to improvements in many products, not only preventive materials for postoperative adhesions, but also pharmaceutical products such as osteoarthritis treatments and cosmetic medicines.