Niederquell, Andreas

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Niederquell
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Andreas
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Niederquell, Andreas

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2020 - 20234
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Autor:in: Vraníková, Barbora ×

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  • Vorschaubild nicht verfügbar
    Publikation
    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, Zdenka [in: International Journal of Pharmaceutics]
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    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, Martin [in: Molecular Pharmaceutics]
    There 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 Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Relevance of the theoretical critical pore radius in mesoporous silica for fast crystallizing drugs
    (Elsevier, 26.10.2020) Vraníková, Barbora; Niederquell, Andreas; Kuentz, Martin [in: International Journal of Pharmaceutics]
    Formulation of poorly water-soluble drugs with mesoporous silica has become a thriving field of pharmaceutics. The theoretical critical pore diameter has been introduced as a maximum value below which an undesired drug crystallization is suppressed by spatial confinement. Currently, only few values have been reported and study of fast crystallising drugs is missing especially at relevant storage temperatures. This study investigated the critical pore diameter of three model drugs with a poor glass-forming ability (i.e. haloperidol, carbamazepine and benzamide) using different mesoporous carriers (Parteck® SLC 500, Neusilin® US2, Syloid® XDP 3050 and Aeroperl® 300 Pharma) and subsequently monitored physical formulation stability over three months by X-ray powder diffraction. The selected drugs showed clear differences in their estimated critical pore diameters, whereas a temperature dependence was barely relevant for pharmaceutical storage conditions. Superior stability was noted for the formulations containing benzamide in line with its predicted relatively large critical pore diameter of 29.5 nm. Contrarily, impaired physical stability depending on drug loading was observed in the case of haloperidol representing a compound with a rather small critical pore diameter (8.4 nm). These findings confirm the importance of estimating the critical pore diameter, especially for poor glass-forming drugs.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Mechanistic aspects of drug loading in liquisolid systems with hydrophilic lipid-based mixtures
    (Elsevier, 30.01.2020) Vraníková, Barbora; Niederquell, Andreas; Ditzinger, Felix; Kuentz, Martin [in: International Journal of Pharmaceutics]
    01A - Beitrag in wissenschaftlicher Zeitschrift