Diclofenac Sodium Adsorption onto Montmorillonite: Adsorption Equilibrium Studies and Drug Release Kinetics

The aim of the present work was to investigate the role of montmorillonite clay as an oral drug delivery carrier for in vitro controlled release of anti-inflammatory drug diclofenac sodium (DS). For this purpose, the adsorption behaviour of DS onto the clay was studied as a function of pH of the aqueous drug solution, contact time, initial drug concentration and clay dosage. The clay–drug composites synthesized were subsequently characterized by X-ray diffraction studies, Fourier transform-infrared studies, differential scanning calorimetric analysis, thermogravimetric analysis, zeta-potential measurement, scanning electron microscopic and high-resolution transmission electron microscopic techniques. A drug loading of 497 mg/g was obtained in case of intercalated clay–drug composite. The in vitro drug release studies of the synthesized clay–drug composites in simulated gastric fluid (pH 1.2) showed no release, whereas a prolonged drug release profile was obtained for the intercalated clay–drug composite in simulated intestinal fluid (phosphate-buffer saline 7.4) in comparison with the pristine drug.