The Experts below are selected from a list of 102 Experts worldwide ranked by ideXlab platform

Kenneth W Olsen - One of the best experts on this subject based on the ideXlab platform.

S B Johns - One of the best experts on this subject based on the ideXlab platform.

J K Schmitt - One of the best experts on this subject based on the ideXlab platform.

David S Hage - One of the best experts on this subject based on the ideXlab platform.

  • characterization of Tolazamide binding with glycated and normal human serum albumin by using high performance affinity chromatography
    Journal of Pharmaceutical and Biomedical Analysis, 2019
    Co-Authors: Zhao Li, Ashley G Woolfork, David S Hage
    Abstract:

    Abstract Sulfonylurea drugs are antidiabetic drugs that are utilized in the treatment of type II diabetes and often have significant binding with human serum albumin (HSA). Immobilized samples of normal or glycated HSA in affinity microcolumns were used to investigate interactions of these proteins with the sulfonylurea drug Tolazamide. HPLC and frontal analysis were used to first examine the overall binding of this drug with these samples of HSA. It was found that Tolazamide had two general classes of binding sites (i.e., high and low affinity) for normal and glycated HSA. The higher affinity sites had binding constants of around 4.3–6.0 × 104 M−1 for these interactions at pH 7.4 and 37 °C, while the lower affinity sites had binding strengths of 4.9–9.1 × 103 M−1. Zonal competition studies between Tolazamide and probes for Sudlow sites I and II on HSA were also performed and used to provide site-specific affinities for Tolazamide at these sites. A decrease of 22% in affinity was observed for Tolazamide at Sudlow site I and an increase up to 58% was seen at Sudlow site II when comparing glycated HSA with normal HSA. These observed changes were compared to those of other first-generation sulfonylurea drugs, providing information on how glycation can alter the total and local binding strength of Tolazamide and related compounds with HSA under levels of glycation seen in patients with diabetes.

Elena V Boldyreva - One of the best experts on this subject based on the ideXlab platform.

  • completing the picture of Tolazamide polymorphism under extreme conditions a low temperature study
    Acta Crystallographica Section C-crystal Structure Communications, 2019
    Co-Authors: Alexey Yu Fedorov, Evgeniy A Losev, Tatiana N Drebushchak, Denis A Rychkov, Elena V Boldyreva
    Abstract:

    We present the results of an experimental and computational study of structural changes in two polymorphs of tolaza­mide {systematic name: 1-[(azepan-1-yl­amino)­carbon­yl]-4-methyl­benzene­sulfonamide}, C14H21N3O3S, on cooling to 100 K and reverse heating. No phase transitions occurred in this temperature range. The anisotropy of the thermal expansion was different for the two polymorphs and differed from that reported previously for the hydro­static compression. The changes in different inter­molecular contacts responsible for the strain anisotropy were analysed. Relative shortening of the contacts was related directly to their initial length and reversely to the steric density around them. Increasing steric density is likely to be the driving force for the con­formational ordering of the azepane ring under compression.

  • effect of pressure on two polymorphs of Tolazamide why no interconversion
    CrystEngComm, 2017
    Co-Authors: Yu A Fedorov, Evgeniy A Losev, Denis A Rychkov, Jernej Stare, Boris A Zakharov, Elena V Boldyreva
    Abstract:

    Two polymorphs of Tolazamide, N-[(azepan-1-ylamino)carbonyl]-4-methylbenzenesulfonamide, a sulfonylurea anti-diabetic drug, have different densities and molecular packings. Polymorph II converts into polymorph I in the solid state on heating or via recrystallization if solvent-assisted. The effect of pressure on the two forms and the possibility of a transformation to a denser form on compression have been studied. No phase transitions have been observed in either of the forms in a pentane–isopentane mixture (when no recrystallization is possible). Polymorph II recrystallized partly into a denser polymorph I in methanol at 0.1 GPa, but the transformation stopped at an early stage. Solid state DFT calculations of the two forms as well as conformational landscape investigation in the gas phase were used to rationalize this result. The anisotropic pressure-induced strain of the two polymorphs has been compared in relation to changes in the hydrogen bond geometry and the behavior of stacking interactions.

  • isoenergetic polymorphism the puzzle of Tolazamide as a case study
    Chemistry: A European Journal, 2015
    Co-Authors: Elena V Boldyreva, Sergey G Arkhipov, Tatiana N Drebushchak, V A Drebushchak, Evgeniy A Losev, A A Matvienko, Vasily S Minkov, Denis A Rychkov, Yurii V Seryotkin, Jernej Stare
    Abstract:

    In the present case study of Tolazamide we illustrate how many seemingly contradictory results that have been obtained from experimental observations and theoretical calculations can finally start forming a consistent picture: a "puzzle put together". For many years, Tolazamide was considered to have no polymorphs. This made this drug substance unique among the large family of sulfonylureas, which was known to be significantly more prone to polymorphism than many other organic compounds. The present work employs a broad and in-depth analysis that includes the use of optical microscopy, single-crystal and powder X-ray diffraction, IR and Raman spectroscopies, DSC, semiempirical PIXEL calculations and DFT of three polymorphs of Tolazamide. This case study shows how the polymorphs of a molecular crystal can be overlooked even if discovered serendipitously on one of numerous crystallizations, and how very different molecular packings can be practically isoenergetic but still crystallize quite selectively and transform one into another irreversibly upon heating.