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/o r 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 p arameters, the peak-width parameters and the preferred orientation par ameter(s), were optimized by a non-linear least-squares procedure. Ort horhombic crystals of isoniazid and D-mannitol were used for the sampl es. Lattice parameters were found to increase slightly with an increas e in compression pressure. In isoniazid, the peak-width broadened with an increase of compression pressure, and a marked broadening at a rel atively high scattering angle was observed. It is indicated that both a decrease of the crystallite size and the lattice disorder occurred s imultaneously with compression. In D-mannitol, the peak-width broadene d with compression and the broadening was independent of the scatterin g 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 compre ssion in both crystals.