Evaluation of swelling processes of various natural polymer matrix tablets by X-ray computed tomography and controlled drug release.

Abstract

The swelling properties and the drug-release sustainability of pre-gelatinized starches (𝛼-starch) tablets depend on the polymer characteristics. In order to clarify the drug release form, the natural polymers (NPs) were investigated. The relationship between drug release and swelling of natural polymers (NPs), the swelling processes of various starch polymers, were investigated using a drug-release test (DRT) and X-ray computed tomography (XCT). NPs consisting of various starches such as glutinous rice starch (GRS), corn starch (CS), and tapioca starch (TS) were used as additives for sustained drug-release tablets. Tablets consisted of 5% theophylline, 94% 𝛼-starch, and 1% magnesium stearate and were compressed at 6 kN. DRTs were measured in distilled water at 37 °C, and the drug concentrations were measured using UV (271 nm). Swelling ratio (R) profiles of the tablets during DRTs were evaluated based on XCT images. The order of the drug-release rate constant of the tablets was TS < GRS < CS. XCT images of the tablets were measured during the DRTs, and CS, GRS, and TS tablets swelled and showed increased gel-layers, and then finally disintegrated at 6, 9, and 11 h, respectively. The relationship between R profile and the % drug release of the tablets differed depending on the kind of NP used.