Influence of barium sulfate X-ray imaging contrast material on properties of floating drug delivery tablets

Abstract

The objective of the study was to reveal the influence of necessarily added barium sulfate (BaSO₄) X-ray contrast material on floating drug delivery tablets. Based on literature survey, a chosen floating tablet composition was determined containing HPMC and carbopol 943P as matrix polymers. One-factor factorial design with five levels was created for evaluation of BaSO₄ (X₁) effects on experimental parameters of tablets including: floating lag time, total floating time, swelling-, erosion-, dissolution-, release kinetics parameters and X-ray detected volume changes of tablets. Applied concentrations of BaSO₄ were between 0 and 20.0% resulting in remarkable alteration of experimental parameters related especially to flotation. Drastic deterioration of floating lag time and total floating time could be observed above 15.0% BaSO₄. Furthermore, BaSO₄ showed to increase the integrity of tablet matrix by reducing eroding properties. A novel evaluation of dissolutions from floating drug delivery systems was introduced, which could assess the quantity of drug dissolved from dosage form in floating state. In the cases of tablets containing 20.0% BaSO₄, only the 40% of total API amount could be dissolved in floating state. In vitro fine resolution X-ray CT imagings were performed to study the volume change and the voxel distributions as a function of HU attenuations by histogram analysis of the images. X-ray detected relative volume change results did not show significant difference between samples. After 24h, all tablets containing BaSO₄ could be segmented, which highlighted the fact that enough BaSO₄ remained in the tablets for their identification.

Keywords: Barium sulfate; Contrast material; Floating drug delivery systems; Floating specific dissolution %; Floating tablet; X-ray CT; X-ray imaging.