VSE knjižnice (vzajemna bibliografsko-kataložna baza podatkov COBIB.SI)
  • Effect of calcium ions on the gelling and drug release characteristics of xanthan matrix tablets
    Baumgartner, Saša, 1969-2015 ; Pavli, Matej ; Kristl, Julijana
    Xanthan is a well known biopolymer. It is an anionic polysaccharide, whose primary structure depends on the bacterial strain and fermentation conditions.Xanthan was extensively studied in combination ... with galactomannans,and over 90 patents cover the technology of this preparation. Our aim was to investigate the relation between the physical properties of a xanthan matrix in the absence or presence of calcium ions and its influence onthe release of pentoxifylline. The release of pentoxifylline from xanthan tablets in purified water was shown to be very slow and governed by the process of polymer relaxation. The presence of calcium ions significantly increased the drug release, changing the release mechanism into a more diffusion controlled one. Xanthan matrices showed substantially faster and more extensive swelling in water than in the presence of Ca2+ ions. Surprisingly, negative correlation between drug release and degree of swellingwas obtained for xanthanČ the higher the swelling, the slower the drugrelease. Higher ionic strength led to lower erosion of xanthan tablets, and the gel layers formed were more rigid and of firmer texture, as shown by rheological experiments and textural profiling. The results indicate that the presence of Ca2+ ions in the solution or in matrices does not cause crosslinking of xanthan polymers, but causes charge screening of ionised groups on the trisaccharide side chains of xanthan, leading to lower inter-molecular repulsion and changing water arrangement. The understanding ofthe parameters influencing drug release leads to the conclusion that xanthanis suitable for controlled release formulations, especially with the incorporation of certain small counterions ionised groups on the trisaccharideside chains of xanthan, leading to lower inter-molecular repulsion and changing water arrangement.
    Vir: European journal of pharmaceutics and biopharmaceutics. - ISSN 0939-6411 (Vol. 69, no. 2, 2008, str. 698-707)
    Vrsta gradiva - članek, sestavni del
    Leto - 2008
    Jezik - angleški
    COBISS.SI-ID - 2218609

    Povezava(-e):

    https://www.sciencedirect.com/science/article/pii/S0939641107003980?via%3Dihub
    DOI

Vnos na polico