The Influence of High Drug Loading in Xanthan Tablets and Media with Different Physiological pH and Ionic Strength on Swelling and Release

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• 作者：Urša Mikac ; Ana Sepe ; Saša Baumgartner ; Julijana Kristl
• 刊名：Molecular Pharmaceutics
• 出版年：2016
• 出版时间：March 7, 2016
• 年：2016
• 卷：13
• 期：3
• 页码：1147-1157
• 全文大小：638K
• ISSN：1543-8392

文摘

The formation of a gel coat around xanthan (Xan) tablets, empty or loaded with pentoxifylline (PF), and its release in media differing in pH and ionic strength by NMR, MR imaging, and two release methods were studied. The T₁ and T₂ NMR relaxation times in gels depend predominantly on Xan concentration; the presence of PF has negligible influence on them. It is interesting that the matrix swelling is primarily regulated by Xan despite high drug loading (25%, 50%). The gastric pH and high ionic strength of the media do not influence the position of the penetration and swelling fronts but do affect the erosion front and gel thickness. The different release profiles obtained in mixing and nonmixing in vitro methods are the consequence of matrix hydration level and erosion at the surface. In water and in diluted acid medium with low ionic strength, the main release mechanism is erosion, whereas in other media (pH 1.2, μ ≥ 0.20 M), anomalous transport dominates as was found out by fitting of measured data with theoretical model. Besides the in vitro investigation that mimics gastric conditions, mathematical modeling makes the product development more successful.