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PurposeImaging methods were used as tools to provide an understanding of phenomena that occur during dissolution experiments, and ultimately to select the best ratio of two polymers in a matrix in terms of enhancement of the dissolution rate and prevention of crystallization during dissolution.MethodsMagnetic resonance imaging, ATR-FTIR spectroscopic imaging and Raman mapping have been used to study the release mechanism of a poorly water soluble drug, aprepitant, from multicomponent amorphous solid dispersions. Solid dispersions were prepared based on the combination of two selected polymers - Soluplus, as a solubilizer, and PVP, as a dissolution enhancer. Formulations were prepared in a ratio of Soluplus:PVP 1:10, 1:5, 1:3, and 1:1, in order to obtain favorable properties of the polymer carrier.ResultsThe crystallization of aprepitant during dissolution has occurred to a varying degree in the polymer ratios 1:10, 1:5, and 1:3, but the increasing presence of Soluplus in the formulation delayed the onset of crystallization. The Soluplus:PVP 1:1 solid dispersion proved to be the best matrix studied, combining the abilities of both polymers in a synergistic manner.ConclusionsAprepitant dissolution rate has been significantly enhanced. This study highlights the benefits of combining imaging methods in order to understand the release process.Electronic supplementary materialThe online version of this article (doi:10.1007/s11095-016-2018-x) contains supplementary material, which is available to authorized users.

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The advantage of magnetic resonance imaging (MRI) is mainly the direct visualization of the physico-chemical processes occurring during the polymer dissolution in real time. Nowadays, polymeric matrices as a means to control the release of the active pharmaceutical ingredient (API) are widely used. Hence it seems necessary to describe the polymer swelling and find the relationship between the type of used polymer and the dissolution profile of API.The aim of our research was to monitor the dissolution kinetics of polymeric matrices with the different ratio of hydrophilic and lipophilic components utilizing MRI technology. For this purpose, six different matrices were prepared. For the dissolution experiments in MRI magnet, plastic flow through cell and tablet holder were designed and manufactured using a 3-D printer. The experiments were performed under specific conditions i.e. phosphate buffer saline pH 6 as a medium, medium temperature - 37°C, the flow rate of medium - 4 ml/min, the time of experiment - 8 hours. To improve the visibility of the erosion front, composite magnetic nanoparticles SiO2/FeOx as a MRI contrast agent were used. Each matrix was measured three times and the thickness of gel layer was evaluated in three different regions. Results from MRI experiments were compared to the results obtained by utilizing the texture analyzer, and then the relationship between polymer swelling and drug release was evaluated.To sum up, MRI turned out to be a suitable imaging method for polymer swelling quantification. For the future measurements, the effect of different additives on the polymer swelling kinetics will be evaluated. The results from the whole research should lead to the database of matrix components and conditions of technological processes and their effects on the dissolution profile of API, thus simplifying the formulation of dosage forms with the desired drug release.