Gastric adhesive-floating pellets for Bolo leaf phenols (BLP) were prepared by extrusion-spheronization method, with chitosan as skeleton bioadhesive material, and stearyl alcohol as help-bleaching agent to evaluate its in vitro adhesivity, floatability and in vivo retention situation, and investigate its in vitro release characteristics. The in vitro adhesivity and floatability were evaluated respectively by in vitro tissue retention method and visual observation method. The retention of pellets in rats was investigated by in vivo tissue retention method and in vivo imaging of small animals. In addition, the in vitro release of p-coumaric acid and caffeic acid as the index components in pellets were evaluated. Results showed that the in vitro adhesivity of the prepared gastric adhesive-floating pellets reached (73.2±3.4)%, and the pellets could float immediately in simulated gastric fluid for more than 12 h; the retention rate of adhesive-floating pellets in rats reached more than 40% after 6 h, while the retention rate of common reference pellets was decreased by 15% as compared with the gastric adhesive-floating pellets, with significant difference (P<0.01); the drug in vitro release time can reach more than 6 h, and the drug release behaviors were lined with Higuchi equation. In vivo and in vitro studies showed that, the gastrointestinal bioadhesive and floating pellets prepared in this study have good bioadhesivity, floatability and good sustained release characteristics.
Keywords: gastric adhesion floating pellets of Bolo leaf phenols; release in vitro; retention of tissue; small animal in vivo imaging; sustained-release.
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