PREFERRED ORIENTATION FO CRYSTALLITES IN TABLETS .6. PATTERN FITTING PROCEDURE FOR THE CHARACTERIZATION OF CRYSTALS AND/OR CRYSTALLITES IN TABLETS

A pattern fitting procedure for the characterization of crystals and/or crystallites in tablets using X-ray powder diffraction data has been described. Observed X-ray diffraction intensities were fitted to the analytic expression, and the fitting parameters, such as the lattice parameters, the peak-width parameters and the preferred orientation parameter(s), were optimized by a non-linear least-squares procedure. Orthorhombic crystals of isoniazid and D-mannitol were used for the samples. Lattice parameters were found to increase slightly with an increase in compression pressure. In isoniazid, the peak-width broadened with an increase of compression pressure, and a marked broadening at a relatively high scattering angle was observed. It is indicated that both a decrease of the crystallite size and the lattice disorder occurred simultaneously with compression. In D-mannitol, the peak-width broadened with compression and the broadening was independent of the scattering angle. It is indicated that although the crystallite size decreased, the lattice disorder did not increase with compression. The strength of the preferred orientation of the crystallites increased with compression in both crystals.