Lipid–Polymer Hybrid Nanoparticles in Microparticle-Based Powder: Evaluating the Potential of Methylprednisolone Delivery for Future Lung Disease Treatment via Inhalation

Background. Lipid–polymer hybrid nanoparticles (LPHNPs) offer a promising method for delivering methylprednisolone (MePD) to treat lung inflammation, addressing aggregation issues seen with polymer-only formulations. Objectives. This study aimed to develop LPHNPs for MePD delivery, assessing their physicochemical properties, drug loading, cytocompatibility, and release profiles, ultimately enabling inhalable microparticle-based powder. Methods. The nanoparticles were formulated using α,β-poly(N-2-hydroxyethyl)-DL-aspartamide-g-Rhodamine B-g-poly(lactic acid) (PHEA-g-RhB-g-PLA) and phospholipids DPPC, DOTAP, and DSPE-PEG2000 in a 45:30:25 weight ratio. Their size, redispersion after freeze-drying, drug loading (DL%), and controlled release were evaluated. Cytocompatibility was assessed on 16-HBE cell lines, measuring anti-inflammatory effects via IL-6 and IL-8 levels. Spray drying was optimized to produce microparticles using mannitol (MAN), leucine (LEU), and N-acetylcysteine (NAC). Results. The nanoparticles had a size of 186 nm and a DL% of 2.9% for MePD. They showed good cytocompatibility, significantly reducing IL-6 and IL-8 levels. Spray drying yielded microparticles with a fine particle fraction (FPF) of 62.3% and a mass median aerodynamic diameter (MMAD) of 3.9 µm. Inclusion of LPHNPs@MePD (0.25% w/v) resulted in FPF and MMAD values of 56.7% and 4.4 µm. In conclusion, this study described the production of novel inhalable powders as carriers for MePD-loaded nanostructures with favorable physicochemical properties, cytocompatibility, and promising aerosol performance, indicating their potential as an effective inhalable therapy for lung inflammation with corticosteroids, especially for treating chronic diseases.