Exploration of alginates as potential stabilizers of nanosuspension

The objective of this study was to explore the feasibility of using alginate as a potential stabilizer of nanosuspension and elaborate the corresponding stabilization mechanism. Using lovastatin as a Biopharmaceutics Classification System (BCS) II drug model, alginate-stabilized nanosuspension was fabricated by the high-pressure homogenization method. The particle size, zeta potential, short-term stability, and dissolution behavior of the nanosuspension were characterized. Thereafter, the surface morphology, crystallinity, redispersability, and stability of the spray-dried nanosuspension were investigated. The spray-dried powder was further compressed into tablets via direct compression, and stressing test was carried out to investigate the stability of nanocrystal loaded tablets. It was demonstrated that alginate could stabilize nanocrystals by providing both electrostatic and steric stabilization, and the effective concentration was much lower than that of the commonly used stabilizers. Good redispersability was achieved after spray drying of the nanosuspension, and the existing state of lovastatin was not changed as indicated by X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC) studies. The stress test indicated that nanocrystal-loaded tablets possessed a favorable stability. In conclusion, alginate could be used as a potential stabilizer of nanosuspension with preferable stabilizing ability at a very low concentration either in liquid or in solid state.