Gum tragacanth-polyvinyl alcohol cryogel and xerogel blends for oral delivery of silymarin: Structural characterization and mucoadhesive property

In this study silymarin (SM) loaded cryo- and xerogels of gum tragacanth-polyvinyl alcohol (GT-PVA) were prepared and their physico-mechanical, microstructural and release properties were investigated. The results showed that unlike cryogels, which were highly porous, xerogels exhibited a densely packed agglomerated microstructure with a continuous network of cracks. The bulk density, mechanical strength and SM retention of xerogels were also much higher than those of cryogels. Furthermore, it was revealed that increasing the ratio of GT adversely influenced both physico-mechanical and structural features of the dried gels, but improved the release profile of SM. Incorporation of SM into the gels led to a distinct enhancement in their porosity, microstructure and physical properties. Rheological measurements indicated that rising the ratio of GT and inclusion of SM increased the viscosity of mucin-polymers blend and improved mucoadhesive property of the gels.