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Structure determination of diclofenac in a diclofenac-containing chitosan matrix using conventional X-ray powder diffraction data

2004; Wiley; Volume: 37; Issue: 2 Linguagem: Inglês

10.1107/s0021889804002353

1600-5767

Nongnuj Muangsin, M. Prajuabsook, Pitiporn Chimsook, Nuanphun Chantarasiri, Krisana Siraleartmukul, Narongsak Chaichit, Supot Hannongbua,

Thermal and Kinetic Analysis

The structure determination of diclofenac embedded in a diclofenac-containing chitosan matrix using conventional X-ray powder diffraction data is demonstrated. It reveals that sodium diclofenac, the starting material in the preparation of a controlled-release diclofenac-containing chitosan matrix, changes to diclofenac acid in space group C 2/ c in the matrix. Simple methods were employed for handling the sample to obtain X-ray powder diffraction data of sufficiently high quality for the determination of the crystal structure of diclofenac embedded in chitosan. These involved grinding and sieving several times through a micro-mesh sieve to obtain a suitable particle size and a uniformly spherical particle shape. A traditional technique for structure solution from X-ray powder diffraction data was applied. The X-ray diffraction intensities were extracted using Le Bail's method. The structure was solved by direct methods from the extracted powder data and refined using the Rietveld method. For comparison, the single-crystal structure of the same drug was also determined. The result shows that the crystal structure solved from conventional X-ray powder diffraction data is in good agreement with that of the single crystal. The deviations of the differences in bond lengths and angles are of the order of 0.030 Å and 0.639°, respectively.