Analysis of Solid-State Interactions of Ketoprofen-Coformer Binary Mixtures by DSC and Hot Stage Microscopy

Ketoprofen is a non-steroidal anti-inflammatory drug with poor water solubility, so the absorption is less than optimal. One method to improve the solubility of ketoprofen is through the formation of multicomponent solid forms. The success of the formation of the multicomponent solid forms is strongly influenced by interactions between components in their solids. In this study, the analysis of the interactions in solid form of ketoprofen-coformers was carried out using the differential scanning calorimetry (DSC) and hot stage microscopy (HSM) with adipic acid and isonicotinamide as coformers. From the experimental results, the mixtures of ketoprofen-adipic acid show a solid-liquid phase diagram that indicates a simple eutectic system with eutectic points on the molar fraction of ketoprofen 0.9 and temperature at 92.9 °C. The ketoprofen-isonicotinamide mixtures have a eutectic system with the peritectic point. The solid-liquid phase diagram has indicated that the ketoprofen-adipic acid in eutectic composition forms a miscible liquid phase without interaction in its solid form, whereas the ketoprofen-isonicotinamide forms a miscible liquid phase accompanied by interaction with the excess component. The results of the HSM analysis showed the same phenomenon as the result of the DSC experiment and have confirmed with the FTIR analysis