Solid dispersions of Celecoxib were prepared with hydroxypropyl beta cyclodextrin by various methods such as physical mixture, cogrinding, kneading, and coevaporation. The dispersions were characterized by differential scanning calorimetry (DSC), X-ray diffraction patterns, infrared spectroscopy, and nuclear magnetic resonance studies. The DSC thermograms of the dispersions indicated potential of heat-induced interaction between Celecoxib and cyclodextrin that could influence in vitro drug dissolution. The dispersions exhibited faster rates of dissolution compared to that of Celecoxib. The kneaded dispersion with the fastest in vitro dissolution rate when compressed into tablets showed a better release profile compared to the tablets of pure Celecoxib. In vivo studies revealed that the kneaded dispersion provided for quicker response and was more effective in inhibiting rat paw edema as compared to Celecoxib alone, thus confirming the advantage of improved pharmacological activity of Celecoxib when administered as a solid dispersion with cyclodextrin.
Piperine, the major alkaloid of black pepper (Piper nigrum L.; Piperaceae), stimulates melanocyte proliferation and dendrite formation in vitro. This property renders it a potential treatment for the skin depigmentation disorder vitiligo. However, piperine does not stimulate melanin synthesis in vitro, and treatments based on this compound may therefore be more effective with concomitant exposure of the skin to ultraviolet (UV) radiation or sunlight. The present study investigated the effect of UVA and simulated solar radiation (SSR) on the chemical stability of piperine, its melanocyte stimulatory effects and its ability to bind protein and DNA. Chromatographic and spectroscopic analysis confirmed the anticipated photoisomerization of irradiated piperine and showed the absence of any hydrolysis to piperinic acid. Isomerization resulted in the loss of ability to stimulate proliferation of a mouse melanocyte cell line, and to bind to human serum albumin. There was no evidence of DNA binding by piperine either before or after irradiation, showing the absence of photoadduct formation by either piperine or its geometric isomers. This is unlike the situation with psoralens, which form DNA adducts when administered with UVA in treating skin diseases. The present study suggests that exposure to bright sunlight should be avoided both during active application of piperine to the skin and in the storage of piperine products. If UVA radiation is used with piperine in the treatment of vitiligo, application of the compound and irradiation should be staggered to minimize photoisomerization. This approach is shown to effectively induce pigmentation in a sparsely pigmented mouse strain.
Procedure for hydrothermal synthesis of ZSM-8-type zeolite crystals, using TEA-OH as a template, in the system having molar compositionat 170 "C is described. Results of characterization of these crystals by XRD, IR, EDAX, SEM, TGA, and adsorption studies are described and discussed. X-ray diffraction studies establish that the crystals are ZSM-8-type with structure similar to that of ZSM-5-type crystals. Crystals have prismatic bipyramidal morphology with average size 18-25 microns. Degased calcined samples adsorb xylenes in the order p > na > 0. Pore length per unit cell, estimated from n-hexane adsorption studies, is 46 A.
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