Bioactive glass/poloxamer 407 hydrogel composite as a drug delivery system: The interplay between glass dissolution and drug release kinetics.

Since patients suffer pain in the post-surgery of bone repair interventions, bioactive glass/hydrogel drug delivery systems containing local anesthetics, such as ropivacaine, could improve patient life quality by combining bone regeneration with anesthetics. However, poloxamer-based hydrogel properties are sensitive to ions, temperature, and water contents and could be structurally influenced by the ionic dissolution products from bioactive glasses of different compositions. Therefore, this study evaluated the interplay between bioactive glass dissolution kinetics and poloxamer 407 properties, establishing a correlation between changes in the hydrogel and drug release kinetics. Three glass compositions were produced, yielding Ca-rich, Na-rich, and an intermediate glass composition. The influence of Ca/Na ratios on the glass structure and dissolution was investigated. Further, the glasses and ropivacaine were incorporated in the poloxamer hydrogel, and the self-assembly ability of poloxamer, the degradation rate, and the drug release kinetics of the composites were evaluated. The results suggested that glass connectivity affected the early-stage of glass dissolution, while sodium mobility influenced the long-term. The dissolution products from the glasses interact with the supramolecular structure of the poloxamer, causing structural changes responsible for hydrogel degradation. Consequently, by changing the Ca/Na ratio in the glasses, it is possible to modulate glass dissolution that, in turn, influences the ropivacaine release. Thus, we propose that the Ca/Na ratio in quaternary bioactive glasses can be used to modulate drug-delivery properties from systems based on bioactive glasses and poloxamer 407.