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2 Ergebnisse
Ergebnisse nach Hochschule und Institut
Publikation Evaluation of gravitational consolidation of binary powder mixtures by modified Heckel equation(Elsevier, 2022) Svačinová, Petra; Macho, Oliver; Jarolímová, Žofie; Gabrišová, Ľudmila; Šklubalová, Zdenka; Kuentz, MartinConsolidation of powders by tapping is an important quality test but it is time and material consuming, which encourages the use of mathematical modelling. This article aims to study this gravitational consolidation dynamics by using nine binary mixtures consisting of cellets and powdered microcrystalline cellulose (MCC102), differing in size, shape, and consolidation properties. To describe the correlation between number of taps and powder bed density/ porosity, the modified Heckel equation. (MH) was newly introduced and compared to the models by Kawakita (KW) and Varthalis & Pilpel (VP). High coefficients of determination were observed by applying the traditional KW model up to 80% of cellets, while a comparable fitting adequacy was obtained with the MH equation up to 50% of cellets in the mixtures. An increased content of MCC102 increased fitting adequacy in the MH and KW model, whereas a nearly opposite mixture trend was observed for the VP model.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Hydroxypropyl Cellulose for Drug Precipitation Inhibition: From the Potential of Molecular Interactions to Performance Considering Microrheology(American Chemical Society, 10.01.2022) Stoyanov, Edmont; Niederquell, Andreas; Kuentz, MartinThere has been recent interest in using hydroxypropyl cellulose (HPC) for supersaturating drug formulations. This study investigated the potential for molecular HPC interactions with the model drug celecoxib by integrating novel approaches in the field of drug supersaturation analysis. Following an initial polymer characterization study, quantum-chemical calculations and molecular dynamics simulations were complemented with results of inverse gas chromatography and broadband diffusing wave spectroscopy. HPC performance was studied regarding drug solubilization and kinetics of desupersaturation using different grades (i.e., HPC-UL, SSL, SL, and L). The results suggested that the potential contribution of dispersive interactions and hydrogen bonding depended strongly on the absence or presence of the aqueous phase. It was proposed that aggregation of HPC polymer chains provided a complex heterogeneity of molecular environments with more or less excluded water for drug interaction. In precipitation experiments at a low aqueous polymer concentration (i.e., 0.01%, w/w), grades L and SL appeared to sustain drug supersaturation better than SSL and UL. However, UL was particularly effective in drug solubilization at pH 6.8. Thus, a better understanding of drug–polymer interactions is important for formulation development, and polymer blends may be used to harness the combined advantages of individual polymer grades.01A - Beitrag in wissenschaftlicher Zeitschrift