pH-sensitive beads containing curcumin loaded nanostructured lipid carriers for a colon targeted oral delivery system

Abstract

Purpose: Drug delivery to the colon via oral administration is limited by early drug release and degradation before reaching the target site. Therefore, this study aimed to develop an orally colon-targeted drug delivery system using a combination of nanostructured lipid carriers (NLCs) entrapped in pH-sensitive beads. Methods: Curcumin-loaded NLCs (curcumin-NLCs), prepared by a hot-melt microemulsion method, were entrapped in pH-sensitive beads (curcumin-NLC beads), EudragitS100 (ES), using an ionotropic gelation method. The physicochemical properties and entrapment efficacy were examined. The in vitro drug release was accomplished under conditions mimicking stomach to colon transition. The kinetic release was analyzed using the DDsolver® program. Results: The curcumin-NLCs showed a mean size of 227.75 ± 0.71 nm with a surface charge of − 55.96 ± 1.88 mV, and a high entrapment efficiency > 90% was observed. The mean size of the curcumin-NLCS beads was 1 mm with a high curcumin entrapment efficiency > 80%. The beads were observed by scanning electron microscope and illustrated a smooth, densely packed structure in which the curcumin-NLCs were evenly embedded in the polymer matrix. The developed system was shown to prevent the drug being released in the stomach. Sustained released behavior over 12 h was observed in the intestine and colon. The release kinetics were fitted to the zero-order model with a release mechanism that followed the Hopfenberg Model, indicating that the drug released through polymer erosion at a constant rate. Conclusion: The developed pH-sensitive bead containing drug-loaded NLCs is a promising carrier for delivering drugs to the colon by oral administration.