Preparation and characterization of zein-based solid dosage form

Abstract

The study aims to investigate the ability of a potential biopolymer – zein either as a dissolution enhancer in solid dispersion system (SDs) or coating material in a novel approach of design single-coated pH-sensitive layer for colon specific delivery system with a poorly water-soluble and stomach-irritable drug – prednisolone (PRL). Firstly, the SDs samples were prepared by solvent – evaporation method and the investigation of drug release was performed according to USP paddle method in stimulated colonic fluid (pH 7.4). The wettability of SDs was studies by means of contact angle measurement. The structure behaviors of solid dispersions were characterized by Powder X-ray diffraction (PXRD) and the molecular interactions between PRL and zein were also determined by Fourier Transform Infrared spectroscopy (FTIR). Next, the core tablets was prepared from the best formulation of PRL SD with zein. These tablets were coated with a one-and-only pH sensitive film combined zein and Kollicoat® MAE 100P at different ratio for coating solutions. Zein-based SDs showed its potential in enhancing the rate of drug release. The powder X-ray diffraction pointed out that there presented the rearrangement of drug’s crystalline structure in some SD samples due to appearance of new peaks on XRD diffractogram, while the forming of hydrogen bond between PRL and zein was also confirmed by FTIR spectra. Moreover, the single-coated layer from the combination of zein and Kollicoat® MAE 100P for delayed release of PRL to colon has showed its potential ability to effectively prevent the liberation of drug from gastric and small intestinal stimulated media and prove successful release of PRL at the expected pH of colon. The results indicated that the dissolution rate of PRL was remarkably improved in the SDs of the drug with this biopolymer. There was a strong relationship between the amount of zein and the dissolution rate of PRL in SDs attribute to zein’s water-resistant property. Also, about the delayed release of drug, the presence of zein in coating solution has improved the properties of Kollicoat® MAE 100P from enteric coating to specific coating layer to deliver drug to lower part of GI tract. The percentage of zein in coating solution is considered as the important factors to achieve the purpose of this study. This work may contribute to the promising material for attempts of pharmaceutical scientist in improvement dissolution rate of poorly water-soluble drug and carry drug to the specific part of the GI tract due to the demand of safety and disease treatment.