Galactomannan (from Gleditsia sinensis Lam.) and xanthan gum matrix tablets for controlled delivery of theophylline: In vitro drug release and swelling behavior

Galactomannan (G) from Gleditsia sinensis Lam. and xanthan gum (X), as sustained release materials for controlled delivery of theophylline, were mixed in different ratios of 7:3, 5:5, and 3:7 to yield enhanced release-controlling performance. The polysaccharides content of tablets was 10% (w/w), either alone or in mixtures. From in vitro dissolution test, G10% and X10% matrices released 91.4 and 87.7% of drug within 24 h, respectively. The synergistic interactions between galactomannan and xanthan effectively retarded the drug diffusion, and the most sustained drug release (75.5% at 24 h) was found in formulation GX7:3. The drug release data fitted to the kinetic model indicated the anomalous transport mechanism (0.5 < n < 1.0). Additionally, the swelling behavior and morphological changes of the tablets were investigated. The results illustrated the potential of binary mixtures of G. sinensis galactomannan and xanthan as novel sustained release materials for controlled drug delivery.