The differences in the interaction of PVP with racemic IBP, enantiomer IBP, and NAP can be related to the differences in their crystal structures. The correlation between the experimental data and the results of the molecular modeling analysis suggest that the IBP dimmer structures are likely to perform HB and aromatic interactions with PVP.

7 A modified method for ibuprofen / β-cyclodextrin (IBU/β-CD) complex formation, 8 based on ball milling (BM) under controlled conditions was developed and its efficiency 9 with respect to the drug encapsulation yield was compared with the well-known kneading 10 and solid dispersion synthetic approaches. Quantitative evaluation of the efficiency of 11 drug-cyclodextrin interaction applying various methods and experimental conditions as 12 well as characterization of the inclusion complexes were carried out by x-ray diffraction 13 (XRD), differential scanning calorimetry (DSC), thermogravimetry (TG), scanning 14 electron microscopy (SEM), infrared (IR) and nuclear-magnetic resonance ( 1 HNMR) 15 spectroscopy. It was found that the yield of the formed IBU / β-CD complex varies in a 16 large range, depending on the techniques applied. The degree of complexation between 17 IBU and β-CD using the proposed optimized BM method is very high and close to the 18 complete inclusion complex formation achieved by a modified solid dispersion method. 19Furthermore, using DSC, TG and 1 HNMR we proved that the ibuprofen molecules enter 20 the β-CD hydrophobic cavities replacing completely the water molecules present naturally 21 inside, which we determined to be 7. 22 23 24

A novel method of preparing modified chitosan films was developed. Bi- and tri-component chitosan films were prepared by blending chitosan with high molecular weight polyoxyethylene. The films were loaded with 8-hydroxy-7-iodoquinoline-5-sulfonic acid which was chosen as a model drug. The properties of the films were studied with respect to crystallinity, thermal stability and swelling degree. These properties were shown to depend on the ratio of polyoxyethylene/chitosan. The drug release profile from the films was measured in a buffer at pH 6.8 and 37°C. The antimycotic effect of the films against Candida albicans was determined.

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A new model aqueous solution of indomethacin was developed on the basis of Pluronic F68 (15%) and F127 (10%). They showed some practical advantages over the models prepared with polyols and polysorbate 80, which were used for comparison. It was found that both Pluronics acted very similarly and were more effective as solubilizers, created an appropriate viscosity, and formed reversible gels at higher temperatures, ensured the indomethacin chemical stability and prolonged in vitro drug diffusion, and showed high physiological tolerance on rabbit eyes. Moreover, indomethacin stability and solution viscosity in the presence of Pluronics did not change after heat sterilization (i.e., the samples can bear heat sterilization).

Ibuprofen/β-cyclodextrin complex was formed applying a modified melting method, consisting in melting only the drug in the mechanical mixture of ibuprofen and β-cyclodextrin. The ibuprofen inclusion into β-CD was monitored by differential scanning calorimetry after initial release of the water molecules from the CD cavity and was proved by X-ray diffraction and FTIR analyses. Keywords: β-cyclodextrin, ibuprofen, inclusion complex, melting method

The phase state and solubility of indomethacin in adsorbates onto hydroxyethylcellulose have been studied. The characterization of the adsorbates and their relevant physical mixtures was made by the use of DSC, X-ray diffractometry, FT-IR spectrometry, and solubility analysis. The drug-to-polymer ratio determines either a partial crystallization of the metastable alpha-form onto hydroxyethylcellulose surface or complete inhibition of indomethacin crystallization. Significantly improved drug aqueous solubility was achieved. A stable immobilization of indomethacin molecules onto hydroxyethylcellulose due to drug/polymer interactions can be assumed. The changed indomethacin phase state in the adsorbates remains stable for one-year storage at ambient conditions. These results could be of practical importance.

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