The usefulness of simple X-ray powder diffraction analysis for counterfeit control--the Viagra example

Counterfeit and illegally manufactured drugs become a very important problem all over the world, hence, a search for new fast, easy, reliable and not expensive methods of drugs screening is essential. We describe the use of X-ray powder diffraction method for the fast screening of tablets for counterfeit medicines identification. The original Viagra tablets and some counterfeit and/or imitations of Viagra were used as example. We demonstrate the application of diffraction method for discrimination of tablets coatings and for identification of differences in drug composition. The X-ray diffraction method turns out to be very fast and reliable for detecting counterfeits and imitation, and it correctly predicts the presence or absence of active substance and/or particular excipients.     

Penciclovir solubility in Eudragit films: a comparison of X-ray, thermal, microscopic and release rate techniques

The solubility of penciclovir (C₁₀N₅O₃H₁₇) in a novel film formulation designed for the treatment of cold sores was determined using X-ray, thermal, microscopic and release rate techniques. Solubilities of 0.15–0.23, 0.44, 0.53 and 0.42% (w/w) resulted for each procedure. Linear calibration lines were achieved for experimentally and theoretically determined differential scanning calorimetry (DSC) and X-ray powder diffractometry (XRPD) data. Intra- and inter-batch data precision values were determined; intra values were more precise. Microscopy was additionally useful for examining crystal shape, size distribution and homogeneity of drug distribution within the film. Whereas DSC also determined melting point, XRPD identified polymorphs and release data provided relevant kinetics.     

差热分析法和近红外漫反射光谱法快速鉴别不同栽培品种的苦荞麦

目的用差热分析法(DTA)和近红外漫反射光谱(NIRS)法对11种栽培苦荞麦进行快速分析鉴别。方法应用TG-DTA热重差热联用仪分别对11个栽培品种苦荞麦进行差热图谱扫描与分析。实验条件为差热量程:±50μV;升温速率:15℃/min;升温范围:35℃～500℃;气氛为氮气,流速:50 ml/min。应用Bruker Vector 22/N型傅立叶变换近红外光谱仪对11种栽培苦荞麦进行扫描。实验条件为测定方式:积分球漫反射;扫描次数64次;扫描范围:3 700～12 000/cm。结果结合两种方法能快速鉴别"建德苦荞麦"同其他苦荞麦,鉴别效果良好。结论 "建德苦荞麦"作为一个新的培育品种,可以对其营养成分、药理活性进行进一步评价,为广泛推广提供参考。     

Structural characterization of p53 isoforms due to the polymorphism at codon 72 by mass spectrometry and circular dichroism

A common polymorphism at codon 72 of human TP53 gene determines a proline to arginine aminoacidic substitution within the proline-rich domain of p53 protein. The two resulting isoforms (p53P⁷² and p53R⁷²) are different from a biochemical and biological point of view and many reports suggest that they can modulate individual cancer susceptibility and overall survival. In the attempt to explain the observed biological differences, we characterized the two isoforms by mass spectrometry and circular dichroism (CD) to evaluate the possible alteration in the secondary structure of p53 introduced by this polymorphism.