Controlled release of sodium diclofena from chitosan/polyethylene glycol beads crosslinked with tripolyphospate

Abstract

The controlled release of diclofenac sodium (DS) from chitosan (CS)/polyethylene glycol (PEG) polyelectrolyte complex hydrogel beads were investigated in simulated gastrointestinal fluid. Following the optimization of the polymer to drug ratio, the chitosan beads were modified by the ionic cross-linking method with varying concentrations and pH of tripolyphosphate (TPP) coagulant solution as well as cross-linking time. The CS/PEG/DS bead obtained with the weight proportion of 1/0.5/0.5 and 10% TPP at pH 6.0 and 30 minutes of cross-linking time was found optimal yielding an excellent encapsulation of over 95% drug loading efficiency. The dissolution profile of DS from CS/PEG beads exhibited that a good slow release profile was achieved after the 5th hour. The drug prolonged release was far more superior upon further cross-linking the hydrogel with glutaraldehyde (GD). The CS/PEG/DS beads cross-linked with both TPP and GD were able to provide the best delayed release in the gastric simulated fluid (pH 1.2). The remaining drug content was gradually released within 24 hours in the intestinal simulated fluid (pH7.4). In all, the CS/PEG beads, beads, cross-linked with TPP and GD, have been proven very useful as a novel alternative for gastrointestinal drug release system.