Development and Evaluation of Monolithic Osmotic Tablet of Ketoprofen: Using Solid Dispersion Technique

Objective: The aim of the present study was to develop and evaluate the monolithic osmotic tablet (MOT) composed of the solid dispersion of ketoprofen (KETO), a poorly water-soluble drug. Solid dispersion technique is generally used for immediate release, as this maximizes the amount of drug absorbed. Sustained release may be obtained by combining solid dispersion technique with MOT so as to increase the therapy efficacy and patient compliance. Methods: Solid dispersion of KETO was prepared by using solvent melt method with polyethylene glycol (PEG) 6000, a hydrophilic carrier. The ratio of KETO to PEG 6000 were 1:1, 1:3 and 1:5 (%w/w). These solid dispersions were characterized by differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA) and powder X-ray diffraction (PXRD) to ascertain whether there were any physicochemical interactions between drug and carrier. The tablet core was prepared by using Polyox N80 (a suspending agent), sodium chloride (an osmotic agent), a solid dispersion consisting of PEG 6000 and KETO followed by a coating of cellulose acetate to make the monolithic osmotic tablet. Results: The results of DSC and PXRD indicated that the drug was in the amorphous state in solid dispersion when PEG 6000 was used as a carrier. The dissolution rate of the solid dispersion was much faster than those for the corresponding physical mixture and pure drug. The optimized MOT formulations were able to deliver KETO at the constant zero order release, above 95% in vitro, independent to environmental media and stirring rate. The release rate of KETO in the MOT is controlled by osmotic pressure, suspending agent and drug solubility in solid dispersion. Conclusion: The monolithic osmotic tablet containing solid dispersion has great potential in the controlled delivery of ketoprofen, a water-insoluble drug.