Hydrogels based on chitosan-xanthan for controlled release of theophylline

The aim of this paper is theophylline (THP) inclusion into xanthan-chitosan polyionic complex (Xa-CS) and the study of its in vitro and in vivo kinetic release. Xa-CS hydrogel was obtained by ionic complexation between two oppositely charged polysaccharides. THP was loaded into the Xa-CS matrix by diffusion of the drug solution. The obtained samples were characterized by FTIR spectroscopy, SEM microscopy and study of the swelling behavior. THP in vitro release experiments were carried out in conditions mimicking the gastrointestinal environment. The chosen drug dose for in vivo study was 15 mg THP/Kg body weight of THP powder or an equivalent dose in complex form. THP serum concentrations were determined by an HPLC assay. The THP peak serum concentration (C(max)) was 7.18 microg/ml for free THP and AUC(0-48) was 25.76 microg h/ml, while in the case of Xa-CS-THP, C(max) was of 5.72 microg/ml and AUC(0-48) = 45.72 microg h/ml. The in vivo study regarding the behaviour of the obtained formulation, showed an increase bioavailability of THP compared to the raw drug, suggesting the possible application of the complex Xa-CS as an oral controlled drug delivery system in the management of chronic pulmonary obstructive disease.