-
[show abstract]
[hide abstract]
ABSTRACT: Accurate, precise and reliable X-ray powder diffraction method was developed for the quantitative determination of famotidine polymorphic forms in their binary mixtures, which slightly outperforms the previously established Raman method. The study highlights the advantage of focused beam transmission geometry in diminishing the effect of preferred orientation in general, and the straightforward transmission foil sample preparation technique in facilitating high-throughput measurements in particular. This combination can provide good quality data for Rietveld refinement which assures more reliable quantitative results than utilizing intensity ratios of selected single reflections. After careful adjustment of profile parameters, simple routine application of the method was achieved.
Journal of pharmaceutical and biomedical analysis 09/2009; 51(3):572-6. · 2.45 Impact Factor
-
Journal of Pharmaceutical Sciences 02/2009; 98(1):378. · 3.06 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: X-ray powder diffractometric and Raman spectrometric methods were developed for quantitative measurement of the polymorphic forms of famotidine in their mixtures. This study aims to deduce some useful conclusions regarding quantitative polymorph analysis, which could also be utilized in industrial practice. Both form A and form B of famotidine possess specific X-ray diffraction reflections as well as characteristic Raman vibrational bands, which permits simple determination of the phases in their mixtures. Keeping in mind that multivariate data processing by chemometric approach is thought of nowadays as superior over univariate one, the results of the two evaluation methods were compared by precision, accuracy as well as robustness. It was found that both approaches provide similar results provided analytically useful data regions are properly selected. Overcoming the common problems of quantitative X-ray powder diffractometry and solid state Raman spectrometry both permit accurate quantification of famotidine polymorphs; the latter, however, seems to be more favourable in regular laboratory practice.
Journal of Pharmaceutical and Biomedical Analysis 01/2009; 49(2):338-46. · 2.97 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Vibrational spectroscopic methods were developed for quantitative analysis of Form II of clopidogrel bisulphate in Form I and Form II polymorphic mixtures. Results show that both IR and Raman spectroscopy combined with chemometrics are suitable to quantify low levels of Form II in Form I, down to 2 and 3%, respectively, with less than 1% limit of detection. Different preprocessing and multivariate methods were applied for spectral processing and were compared to find the best chemometric model. Common problems of quantitative vibrational spectroscopy in the solid phase are discussed; and procedures appropriate to eliminate them are proposed.
Journal of Pharmaceutical and Biomedical Analysis 11/2008; 49(1):32-41. · 2.97 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Bicalutamide, an active pharmaceutical ingredient possessing antiandrogenic activity, is known to exhibit polymorphism. The higher melting Form I relates monotropically to the lower melting Form II. The amorphous form can be easily produced by quench cooling the melt, but it is known to crystallize spontaneously to Form II at room temperature within days. Our results show that crystallization of amorphous bicalutamide is greatly influenced by experimental conditions and sample treatment. The effect of mechanical activation on the polymorph transitions is investigated in detail. Seeds of Form I can be formed in the amorphous phase even due to gentle mechanical treatment, which results in crystallization to the more stable structure at elevated temperature. The crystalline Form II may as well be transformed to the stable modification through mechanical activation at elevated temperature.
Journal of Pharmaceutical Sciences 01/2008; 97(8):3222-32. · 3.06 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The effects of high static pressure on the polymorphic modifications A and B of famotidine were examined by differential scanning calorimetry, infrared and Raman spectroscopy, and X-ray powder diffractometry. The obtained effects appeared to differ significantly depending on whether they were monitored by DSC or any of the other above techniques. In particular, DSC measurements tend to deceptively amplify a tendency of the pure modification B to turn into the more stable form A under pressurization, while the spectroscopic methods and XRPD exhibit no essential change in the crystal structure of the metastable form B. The apparent morphological transformation in the pressed samples stems from the nature of the DSC method itself.
Thermochimica Acta 430:35-41. · 1.80 Impact Factor
