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120 Ergebnisse
Bereich: Suchergebnisse
Publikation Study of disordered mesoporous silica regarding intrinsic compound affinity to the carrier and drug-accessible surface area(ACS, 2023) Niederquell, Andreas; Vraníková, Barbora; Kuentz, MartinThere is increasing research interest in using mesoporous silica for the delivery of poorly water-soluble drugs that are stabilized in a noncrystalline form. Most research has been done on ordered silica, whereas far fewer studies have been published on using nonordered mesoporous silica, and little is known about intrinsic drug affinity to the silica surface. The present mechanistic study uses inverse gas chromatography (IGC) to analyze the surface energies of three different commercially available disordered mesoporous silica grades in the gas phase. Using the more drug-like probe molecule octane instead of nitrogen, the concept of a “drug-accessible surface area” is hereby introduced, and the effect on drug monolayer capacity is addressed. In addition, enthalpic interactions of molecules with the silica surface were calculated based on molecular mechanics, and entropic energy contributions of volatiles were estimated considering molecular flexibility. These free energy contributions were used in a regression model, giving a successful comparison with experimental desorption energies from IGC. It is proposed that a simplified model for drugs based only on the enthalpic interactions can provide an affinity ranking to the silica surface. Following this preformulation research on mesoporous silica, future studies may harness the presented concepts to guide formulation scientists. © 2023 American Chemical Society.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Comparative drug solubility studies using shake-flask versus a laser-based robotic method(Springer, 2023) Rahimpour, Elaheh; Moradi, Milad; Sheikhi-Sovari, Atefeh; Rezaei, Homa; Rezaei, Hadis; Jouyban-Gharamaleki, Vahid; Kuentz, Martin; Jouyban, AbolghasemDrug solubility is of central importance to the pharmaceutical sciences, but reported values often show discrepancies. Various factors have been discussed in the literature to account for such differences, but the influence of manual testing in comparison to a robotic system has not been studied adequately before. In this study, four expert researchers were asked to measure the solubility of four drugs with various solubility behaviors (i.e., paracetamol, mesalazine, lamotrigine, and ketoconazole) in the same laboratory with the same instruments, method, and material sources and repeated their measurements after a time interval. In addition, the same solubility data were determined using an automated laser-based setup. The results suggest that manual testing leads to a handling influence on measured solubility values, and the results were discussed in more detail as compared to the automated laser-based system. Within the framework of unavoidable uncertainties of solubility testing, it is a possibility to combine minimal experimental testing that is preferably automated with mathematical modeling. That is a practical suggestion to support future pharmaceutical development in a more efficient way. © 2023, The Author(s), under exclusive licence to American Association of Pharmaceutical Scientists.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Corrigendum to “Powder cohesion and energy to break an avalanche. Can we address surface heterogeneity?” [Int. J. Pharm. 626 (2022) 122198](Elsevier, 2023) Brokešová, Jana; Niederquell, Andreas; Kuentz, Martin; Zámostný, Petr; Vraníková, Barbora; Šklubalová, Zdenka01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Not the usual suspects. Alternative surfactants for biopharmaceuticals(American Chemical Society, 2023) Brosig, Sebastian; Cucuzza, Stefano; Serno, Tim; Bechtold-Peters, Karoline; Buecheler, Jakob; Zivec, Matej; Germershaus, Oliver; Gallou, Fabrice01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Using a laser monitoring technique for dissolution and thermodynamic study of celecoxib in 2-propanol and propylene glycol mixtures(Dissolution Technologies, 2023) Jouyban-Gharamaleki, Vahid; Martinez, Fleming; Kuentz, Martin; Rahimpour, Elaheh; Jouyban, Abolghasem01A - Beitrag in wissenschaftlicher ZeitschriftPublikation 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 ZeitschriftPublikation Study and computational modeling of fatty acid effects on drug solubility in lipid-based systems(Elsevier, 06/2022) Wyttenbach, Nicole; Ectors, Philipp; Niederquell, Andreas; Kuentz, MartinLipid-based systems have many advantages in formulation of poorly water-soluble drugs but issues of a limited solvent capacity are often encountered in development. One of the possible solubilization approaches of especially basic drugs could be the addition of fatty acids to oils but currently, a systematic study is lacking. Therefore, the present work investigated apparently neutral and basic drugs in medium chain triglycerides (MCT) alone and with added either caproic acid (C6), caprylic acid (C8), capric acid (C10) or oleic acid (C18:1) at different levels (5 – 20%, w/w). A miniaturized solubility assay was used together with X-ray diffraction to analyze the residual solid and finally, solubility data were modeled using the conductor-like screening model for real solvents (COSMO-RS). Some drug bases had an MCT solubility of only a few mg/ml or less but addition of fatty acids provided in some formulations exceptional drug loading of up to about 20% (w/w). The solubility changes were in general more pronounced the shorter the chain length was and the longest oleic acid even displayed a negative effect in mixtures of celecoxib and fenofibrate. The COSMO-RS prediction accuracy was highly specific for the given compounds with root mean square errors (RMSE) ranging from an excellent 0.07 to a highest value of 1.12. The latter was obtained with the strongest model base pimozide for which a new solid form was found in some samples. In conclusion, targeting specific molecular interactions with the solute combined with mechanistic modeling provides new tools to advance lipid-based drug delivery.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Validation of UHPLC–MS/MS methods for the determination of kaempferol and its metabolite 4-hydroxyphenyl acetic acid, and application to in vitro blood-brain barrier and intestinal drug permeability studies(Elsevier, 05.09.2016) Moradi-Afrapoli, Fahimeh; Oufir, Mouhssin; Walter, Fruzsina R.; Deli, Maria A.; Smiesko, Martin; Zabela, Volha; Butterweck, Veronika; Hamburger, Matthias01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Saponins from saffron corms inhibit the gene expression and secretion of pro-inflammatory cytokines(American Chemical Society, 18.02.2021) Keller, Morris; Fankhauser, Sarah; Giezendanner, Noreen; König, Michelle; Keresztes, Franziska; Danton, Ombeline; Fertig, Orlando; Marcourt, Laurence; Butterweck, Veronika; Potterat, Olivier; Hamburger, MatthiasCorms are obtained as a byproduct during the cultivation of saffron (Crocus sativus). In a project aimed at the valorization of this waste product, we observed that a 70% EtOH extract of the corms and a sugar-depleted MeOH fraction of the extract inhibited the TNF-α/IFN-γ-induced secretion and gene expression of the chemokines IL-8, MCP-1, and RANTES in human HaCaT cells. The effects were in part stronger than those of the positive control hydrocortisone. For preparative isolation, the 70% EtOH extract was partitioned between n-BuOH and water. Separation of the n-BuOH-soluble fraction by centrifugal partition chromatography, followed by preparative and semipreparative HPLC, afforded a series of bidesmosidic glycosides of echinocystic acid bearing a 3,16-dihydroxy-10-oxo-hexadecanoic acid residue attached to the glycosidic moiety at C-28. They include azafrines 1 and 2, previously reported in saffron, and eight new congeners named azafrines 3–10. Saffron saponins significantly inhibited TNF-α/IFN-γ-induced secretion of RANTES in human HaCaT cells at 1 μM (p < 0.001). Some of them further lowered TNF-α/IFN-γ-induced gene expression.01A - Beitrag in wissenschaftlicher Zeitschrift