Nimesulide Apparent Solubility Enhancement with Natural Cyclodextrins and their Polymers

The object of this work is to investigate physicochemical characteristics and inclusion behavior of binary systems based on cyclodextrin polymer (Poly-CD) or native cyclodextrins (CDs) with a poorly water-soluble, nonsteroidal anti-inflammatory drug, nimesulide (NIM) chemically, N-(4-nitro-2-phenoxyphenyl)methanesulfonamide. Our formulations were studied in solution and solid-state. Drug-cyclodextrin solid binary systems were prepared by the freezedrying method. Phase solubility study was used to evaluate the interaction in solution, between NIM/CDs and NIM/(Poly- CD). The stability constants of NIM/CDs and NIM/(Poly-CD) complexes were calculated using the phase solubility method. The apparent solubility of NIM was enhanced especially with Poly-α-CD (up to78-fold) in neutral aqueous solutions without any organic solvents or surfactants. Copmlexes formation was confirmed, in the solid state, by differential scanning calorimetry, infrared spectroscopy and DRX. Complexation spontaneity of drug with cyclodextrin polymers was highlighted using ΔG°values.