Preparation and Characterization of Prednisolone-Loaded Solid Lipid Nanoparticles for Potential Transdermal...

Transdermal delivery of prednisolone using solid-lipid nanoparticles (SLN) offers a promising strategy to enhance drug administration by enabling direct transport through the skin into the systemic circulation. However, the impact of processing conditions on the physicochemical properties and release mechanisms of prednisolone‑loaded SLN remains insufficiently explored.

The present study developed prednisolone-loaded SLN using an emulsification-homogenization- ultrasonication approach. Key process parameters, namely homogenization stirring speed and duration, as well as ultrasonication time, temperature, and power, were systematically refined based on particle size, polydispersity index (PDI), and zeta potential. The selected formulation was further characterized for entrapment efficiency (EE), drug loading (DL), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and in vitro drug release.

The experimentally determined DL ranged from 8.52 ± 0.55 to 9.89 ± 1.73%, corresponding to 85-99% of the intended loading, indicating minimal processing loss. Formulation H3, selected for further characterization based on its physicochemical profile, was homogenized at 10,000 rpm for 4 minutes, followed by ultrasonication at 60°C and 60 W for 4 minutes. H3 exhibited a particle size of 319.00 ± 56.15 nm, a PDI of 0.48 ± 0.022, a zeta potential of -19.86 ± 9.56 mV, and an EE of 98.25 ± 0.49%. All formulations demonstrated sustained drug release over 24 h with no statistically significant differences observed among them (p = 0.148).

Kinetic modeling showed that both Higuchi and Korsmeyer-Peppas models adequately described the release profile of H3, suggesting heterogeneous release behavior involving overlapping diffusion- and matrix- related mechanisms. ATR-FTIR and DSC analyses indicated alterations in intermolecular interactions and lipid packing behavior following nanoparticle formation, while TEM confirmed spherical morphology and absence of visible aggregation, consistent with successful formation of the SLN system.

Prednisolone-loaded SLN prepared using emulsification-homogenization-ultrasonication demonstrated favorable physicochemical properties and sustained release behavior governed by combined diffusion and matrix-related processes. Further studies on long-term stability, as well as ex vivo and in vivo skin permeation, are required to confirm their suitability for transdermal application.