Solid state stability of ketoprofen in the presence of different excipients

Physical mixtures of ketoprofen (KT) were prepared using different excipients, namely, lactose, mannitol, sorbitol, beta-cyclodextrin, polyvinylpyrolidone (PVP) K30, polyethyleneglycol (PEG) 20,000 and urea in a ratio of 2:1 (drug/excipient). The prepared samples as well as KT alone were stored at 40, 50 and 60 degrees C in sealed glass vials for 12 weeks. The fresh and stored samples were subjected to physical examination and instrumental analysis including m.p., IR and dissolution rate. KT without additives was found to be physically stable or when mixed with either lactose, mannitol, sorbitol or beta-cyclodextrin for 12 weeks at 60 degrees C. The m.p. of the drug alone or in presence of these excipients did not change. Also IR showed no change. On the other hand, KT mixtures with PVP K30, PEG 20,000 or urea were physically unstable on storage at 40, 50 and 60 degrees C. Their m.p. were found to decrease; the IR curves were also changed. All the tested excipients enhanced the dissolution of KT from its physical mixtures and could be arranged according to the extent of dissolution as follows: Lactose = Mannitol > beta-cyclodextrin > PVP K30 = Urea > Sorbitol > PEG 20,000.