Rheological and Structural Study of Solid Lipid Microstructures Stabilized within a Lamellar Gel Network

Purpose This study aimed to investigate the influence of different ratios and amounts of cetyl and stearyl fatty alcohols in interaction with cetyl palmitate fatty acid ester as they are responsible for the rheological and microstructural modifications in the SLMs. Methods SLMs were prepared as ternary systems in the absence of an oil phase; Tween 80 was selected as nonionic surfactant that was blended with the fatty amphiphiles forming the lipid phase, and ultra-purified water constituted the aqueous phase; the hot emulsification and high shear homogenization methods were used to produce the SLMs, and central composite face design was used to evaluate and model the SLMs particles size, polydispersity, and rheological parameters. Results The formulated SLMs have an average particle size ranging from 18.4 to 59.4 mu m which showed that the lipids' ratio and amount have affected significantly (p < 0.05) the rheological and microscopic parameters, and the optimization led to lipid combination of SA/CA/CP/0.41:0.41:0.18 with a consistent structure and shear thinning behavior. The drug-loaded SLMs have a sustained release profile up to 12 h with a release rate ranged from 1.6 to 2.6 mg/h for 12% and 9% lipids content formulations. Conclusion The rheological and microstructural behaviors of the studied SLMs are strongly related with the swelling capacity of the formed gel network, while their ratios, amounts, and storage time controlled the structure. The findings in this study may provide further insights of SLMs rheological and structural behaviors in different dispersion mixtures.