Solubility enhancement of ibuprofen by adsorption onto spherical porous calcium silicate

Abstract

The solubility of a drug is higher when it is in an amorphous form than when it is in a crystalline form. To enhance the solubility of ibuprofen (IBU), a poorly water-soluble drug, we attempted to adsorb IBU onto spherical porous calcium silicate (Florite® PS300, PS300) in two ways: the evaporation (EV) and sealed heating (SH) methods. The crystallinity of the samples was evaluated using powder X-ray diffraction analysis (PXRD) and differential scanning calorimetry (DSC). The molecular interaction between IBU and PS300 was evaluated with FTIR. In addition, the dissolution behavior of IBU in the samples was assessed by the dissolution test. Based on the results of the PXRD and DSC measurements, both methods allowed adsorption of IBU onto PS300, and IBU was amorphized. Based on the FTIR observations, in the SH or EV mixtures containing 10% and 30% IBU, respectively, it seemed that the IBU molecules intermolecularly interacted with calcium molecules as the main component of PS300. Improvement in the solubility of IBU was observed with both methods; however, the dissolution rate of IBU from samples prepared via SH was higher than that from EV, or of IBU crystals. Collectively, our findings indicate that the petal-like structure of PS300, which has a spherical shape and good flowability, is an effective tool for adsorbing IBU onto PS300 via SH.