pH-Sensitive Tacrolimus loaded nanostructured lipid carriers for the treatment of inflammatory bowel disease

Inflammatory Bowel Disease is the chronic tissue inflammation of the lower part of the Gastrointestinal tract (GIT). Conventional therapeutic approaches face numerous challenges, often making the delivery system inadequate for treating the disease. This study aimed to integrate a pH-sensitive polymer and nanostructured lipid carriers (NLCs) to develop a hybrid nanocarrier system. Tacrolimus-loaded NLCs coated with Eudragit® FS100 (TAC-NLCs/E FS100) nanoparticles were prepared via double emulsion technique followed by an aqueous enteric coating technique. Various parameters, such as particle size, entrapment efficiency, and zeta potential were optimized using Design Expert software®. Cetyltrimethyl ammonium bromide (CTAB) was used as a cationic surfactant which induces a positive charge on the nanoparticles. These cationic NLCs can adhere to the mucosal surface, thereby enabling prolonged retention. In vitro drug release was assessed, and the results demonstrated that drug release was retarded at pH 1.2 corresponding to upper GIT pH and maximum drug was released at pH 7.4 (colonic pH). Moreover, we evaluated TAC-NLCs/E FS100 nanoparticles in murine colitis models to gauge the efficacy of both coated and uncoated NLCs formulation. The TAC-NLCs/E FS100 showed a pronounced reduction in induced colitis, as evident from the restoration of morphological features, improved histopathological scores, antioxidant levels, and decreased the levels of proinflammatory cytokines. Thus, pH-sensitive TAC-NLCs/EFS 100 are attributed to the enhanced localization and targeted delivery at the specific site.