Evaluation of the Controlled Release Ability of Theophylline from Xanthan/Chondroitin Sulfate Hydrogels

The xanthan/chondroitin sulfate (X/CS) hydrogels, obtained by a crosslinking technique, were evaluated in vitro and in vivo as matrices for theophylline release. The influence of pH of simulated physiological media on the X/CS swelling behaviour at 37 ̊C was investigated. The hydrogels theophylline loading degree was evaluated by near infrared chemical imaging (NIR-CI) technique and confirmed also by FT-IR spectroscopy; the drug loading was about 77.5% based on PLS-DA prediction (Partial least squares-Discriminate Analysis). The release profiles of theophylline from X/CS hydrogels in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) depend on CS content. The release mechanisms were controlled by the drug solubility and ionic properties of the polymers. In vivo theophylline delivery was done by oral administration. Pharmacokinetic analysis revealed sustained-release characteristics for 50/50 X/CS theophylline-loaded formulation compared with raw theophylline which was rapidly absorbed, distributed and eliminated. A good in vitro-in vivo correlation was found.