A series of vanadocene complexes [Cp′2V(L)][OTf]2 (Cp′ = η5‐C5H5, η5‐C5H4Me; L = phen, 5‐NO2‐phen, 5‐NH2‐phen, 4,7‐Ph2‐phen) was prepared and characterized by mass spectrometry and EPR spectroscopy. Structures of two complexes that contain an N,N′‐chelating ligand, [(η5‐C5H4Me)2V(phen)][OTf]2·0.5Me2CO and [(η5‐C5H5)2V(5‐NH2‐phen)][OTf]2, and the triflate intermediate [(η5‐C5H5)2V(OTf)2] were further confirmed by X‐ray diffraction analysis. The cytotoxicity study has shown that complexes that contain phenanthroline ligands have considerably higher in vitro activity toward human leukemia cells MOLT‐4 and HL‐60 than their parent dichlorides ([Cp′2VCl2]). The high activity of these complexes coheres with their higher stability in various aqueous media. This study has further shown that substitution of chloride ligands in the vanadocene dichloride has a considerably higher effect on cytotoxicity than expected on the basis of established mechanistic rules.

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Good flow and compaction properties are necessary for the manipulation of particulate material in the pharmaceutical industry. The influence of the addition of an alternative sweetener, rebaudioside A, in a concentration 0.2% w/w and 0.5% w/w on the flow, shear and compaction properties of sorbitol for direct compaction, Merisorb 200, was investigated in this work. Rebaudioside A worsened the flow properties of sorbitol: the Hausner ratio, the compressibility index and the mass flow rate through the aperture of a model hopper. Using a Jenike shear cell revealed a significant increase in cohesion leading to the decrease of the flow function; moreover, the addition of rebaudioside A increased the total energy for compression of tablets and plasticity estimated by the force-displacement method. Finally, the tablets showed a higher tensile strength and needed longer time to disintegrate compared to the tablets made of sorbitol itself. In view of the results for the free-flowable excipient, sorbitol, the effects of stevia even for a 0.2% w/w concentration have to be carefully considered, particularly whenever used in pharmaceutical formulations of poor flow properties.

Flowability is among the most important properties of powders, especially when fine particle size fractions need to be processed. In this study, our goal was to find a possibly simple but accurate mathematical model for predicting the mass flow rate for different fractions of the pharmaceutical excipient sorbitol for direct compression. Various regression models derived from the Jones–Pilpel equation for the prediction of the mass flow rate were investigated. Using validation with experimental data for various particle and hopper orifice sizes, we focused on the prediction accuracy of the respective models, i.e., on the relative difference between measured and model-predicted values. Classical indicators of regression quality from statistics were addressed as well, but we consider high prediction accuracy to be particularly important for industrial processing in practice. For individual particle size fractions, the best results (an average prediction accuracy of 3.8%) were obtained using simple regression on orifice size. However, for higher accuracy (3.1%) in a unifying model, valid in the broad particle size range 0.100–0.346 mm, a fully quadratic model, incorporating interaction between particle and orifice size, appears to be most appropriate.