Mechano-chemical formation of indomethacin β cyclodextrin inclusion compounds in powder phase roll mixtures

Preparation and Characterization of Indomethacin Supramolecular Systems with β-Cyclodextrin in Order to Estimate Photostability Improvement

Cyclodextrins have found wide application in contemporary chemistry, pharmacy and medicine. Because of their unique properties, cyclodextrins are constantly used in research on solubility or stability improvement, as well as other physicochemical properties of medicinal substances. Indomethacin (IND) is a photolabile molecule that also attracts the interest of researchers due to its therapeutic potential and the need to overcome its problematic photosensitivity. Supramolecular complexes of indomethacin with β-cyclodextrin (CD) are already known, and they show greater stability compared to complexes with other types of cyclodextrins. So far, however, the sensitivity to light of physical mixtures and inclusion complexes in the solid phase has not been studied, and their various stoichiometries have not yet been investigated. Due to this fact, the aim of the present study is to obtain supramolecular systems (inclusion complexes and physical mixtures) of indomethacin with three different amounts of β-cyclodextrin. Assessment of the photochemical stability of indomethacin-β-cyclodextrin systems in the solid state is performed in order to find the best correlation between IND stability and the amount of CD. Comparative analysis of physicochemical degradation for stoichiometry systems [CD:IND] = [1:1], [0.5:1] and [0.1:1] is performed by using ultraviolet spectroscopy, transmission—FTIR, reflection—ATR-FTIR infrared spectroscopy and DSC calorimetry.

Nimesulide/methyl β-cyclodextrin inclusion complexes: physicochemical characterization, solubility, dissolution, and biological studies

Nimesulide (NIM) is an insoluble nonsteroidal anti-inflammatory drug (NSAID). Complexation of drug with methyl β-cyclodextrin was evaluated to improve solubility and dissolution rate of NIM. Complexation was achieved via a coevaporation technique to obtain different drug to polymer molar ratios (1:1, 1:2, and 1:3). The physicochemical characterization of the systems using powder X-ray diffraction and infrared spectroscopy was carried out to understand the influence of this technological process on the physical status of single components and complex systems and to detect possible interactions between drug and carrier. Moreover, quantitative solubility and in vitro dissolution studies of NIM alone and NIM inclusion complexes were studied in the dissolution media of phosphate buffer pH 5.5 and 7.4. The analysis provided existence of a molecular interaction between drug and carrier together in the complex state. The study showed that the inclusion systems enhanced of drug solubility, dissolution rate, and anti-inflammatory activity.

Diclofenac-beta-cyclodextrin binary systems: physicochemical characterization and in vitro dissolution and diffusion studies

The aim of this work was to study the influence of beta-cyclodextrin (beta-CD) on the biopharmaceutic properties of diclofenac (DCF). To this purpose the physicochemical characterization of diclofenac-beta-cyclodextrin binary systems was performed both in solution and solid state. Solid phase characterization was performed using differential scanning calorimetry (DSC), powder x-ray diffractometry (XRD), and Fourier transform infrared spectroscopy (FTIR). Phase solubility analyses, and in vitro permeation experiments through a synthetic membrane were performed in solution. Moreover, DCF/beta-CD interactions were studied in DMSO by 1H nuclear magnetic resonance (NMR) spectroscopy. The effects of different preparation methods and drug-to-beta-CD molar ratios were also evaluated. Phase solubility studies revealed 1:1 M complexation of DCF when the freeze-drying method was used for the preparation of the binary system. The true inclusion for the freeze-dried binary system was confirmed by 1H NMR spectroscopy, DSC, powder XRD, and IR studies. The dissolution study revealed that the drug dissolution rate was improved by the presence of CDs and the highest and promptest release was obtained with the freeze-dried binary system. Diffusion experiments through a silicone membrane showed that DCF diffusion was higher from the saturated drug solution (control) than the freeze-dried inclusion complexes, prepared using different DCF-beta-CD molar ratios. However, the presence of the inclusion complex was able to stabilize the system giving rise to a more regular diffusion profile.

Preparation and Clinical Application of Indomethacin Gel for Medical Treatment of Stomatitis

The preparation and clinical applications of indomethacin (IM) gel were investigated in the treatment of stomatitis resulting from chemotherapy and radiotherapy for cancer. IM gel was prepared by adding various water-soluble polymers [hydroxypropyl cellulose (HPC), etc.] to IM aqueous solution. The release rate of IM from IM gels was found to decrease with increasing polymer concentration and viscosity and to follow a first-order reaction rate equation. The release rate of IM from the IM gel with HPC was decreased gradually with increasing polymer concentration and to be easily controllable compared with gels with other polymers. The time before pain relief occurred after application of the IM gel was slightly shorter and the duration of pain relief was longer compared with the IM aqueous solution. It was confirmed that IM gel is useful in the treatment of stomatitis.

Characterisation of nimesulide-betacyclodextrins systems prepared by supercritical fluid impregnation

The purpose of this study was to apply the supercritical CO(2) impregnation process for preparing solvent-free nimesulide (NMS)-betacyclodextrins (BCD) association systems with enhanced drug dissolution rate. Several drug-to-carrier molar ratios were tested (1:1; 1:2.5; 1:3.5) at different conditions of temperatures (40, 100, and 130 degrees C) and pressures (140, 190 or 220 bar). The physical and morphological characterisation of the systems using powder X-ray diffraction, thermal analysis, diffuse reflectance Fourier transform-infrared spectroscopy and scanning electron microscopy was carried out to understand the influence of this technological process on the physical status of single components and binary systems and to detect possible interactions between drug and carrier. These analyses provided no evidence of a complete inclusion of NMS in the carrier but the existence of interactions between drug and carrier together with a partial dehydration of the BCD and the formation of drug crystallites with lower melting point and heat of fusion than the native NMS. These phenomena were more intense when severe conditions of pressure and temperature (220 bar and 130 degrees C) were used during impregnation trials and when the amount of BCD augmented in the systems. These activated solid state of the impregnated systems promoted an enhancement of drug dissolution rate that, in keeping with the results of the physical characterisation, was function of the process conditions and BCD content.

Interactions between n-octyl and n-nonyl β-d-glucosides and α- and β-cyclodextrins as seen by self-diffusion NMR

In this work (1)H NMR self-diffusion experiments have been performed to determine the self-diffusion coefficients of n-octyl beta-d-glucoside and n-nonyl beta-d-glucoside in alpha-cyclodextrin and beta-cyclodextrin solutions at 25 degrees C. Two questions are addressed. The first concerns the general influence on nonionic surfactant transport properties when cyclodextrins are present in solution. The second question concerns the influence of surfactant-chain length and cyclodextrin cavity volume on the association constant. The self-diffusion coefficients of the alkyl glucosides, in cyclodextrin-containing solutions, depend on the cyclodextrin concentration on account of the formation of complexes. The cyclodextrin diffusion is only mildly influenced, since the complex has similar diffusion coefficients as the free cyclodextrin. There are some obstruction effects at the highest surfactant concentrations which decrease the cyclodextrin diffusion. A set of equations to model the self-diffusion coefficients of the surfactant and cyclodextrin was developed and is presented. On the basis of such equations, properties such as association constants, and micelle and complex diffusion coefficients can be estimated.

Stability of amorphous indomethacin compounded with silica

The stability of indomethacin (IM) compounded with SiO(2) either by co-grinding or by melt-quenching was examined by recrystallization kinetics under the conditions 30 degrees C and 11% relative humidity. A decrease of the recrystallization rate with and without an appreciable induction period was observed in both compounds. Higher stability of amorphous IM compounded with SiO(2) was attained by prolonged co-grinding than by melt-quenching. This was explained by the stronger chemical interaction at the interface between IM and SiO(2) by co-grinding, as revealed by (29)Si and (13)C solid state NMR. Incomplete co-grinding with the rest of the crystalline state, however, made the amorphous state appreciably unstable, since the remaining crystallites serve as seeds for recrystallization.