Analysis of swelling and dissolution dynamics of xanthan gum-excipient blends using dissolution imaging

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This research investigates how dissolution imaging can elucidate the impact of excipients with various solubility profiles (lactose, microcrystalline cellulose, and dicalcium phosphate) on the swelling and drug release properties of xanthan gum (XG) compacts using a dissolution imaging technique. Xanthan gum was mixed with the excipients in various ratios after which tablet surface characteristics and dissolution investigations were conducted to determine their impact on the swelling and drug release behaviours of the various compacts. The results from focus variation microscopy showed that the 1:3 XG:lactose compacts displayed lower Smr2 values, suggesting the greater likelihood of these compacts for initial wetting. The swelling studies from dissolution imaging revealed that the 3:1 XG:excipient, where there was a higher XG content, lead to the development of a more extensive gel layer. The incorporation of either lactose, microcrystalline cellulose or dicalcium phosphate into the XG compacts resulted in an increased rate of drug release when compared to the pure XG compacts. The amount of XG present in the compacts was therefore important in determining the drug retention capacity of the matrix. Such findings demonstrate the importance of dissolution imaging in providing qualitative and quantitative insights into the dissolution phenomena with value in the designing of drug delivery formulations with tailored release profiles. • Lactose, MCC and DCP used at different ratios within XG compacts influence drug release and swelling. • The higher content of the lactose, MCC or DCP within the XG compacts displayed lower Smr2 values, indicating higher initial wetting. • Compacts with higher XG concentration (3:1) ratios develop more extensive gel layers thus enhancing drug retention. • The incorporation of the excipients into the XG compacts increased the rate and extent of drug release when compared to the pure XG compacts. • Dissolution imaging shows important details about swelling behaviour and drug release.