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Pharmaceutics Aug 2021Taxifolin, also known as dihydroquercetin, possesses several interesting biological properties. The purpose of the study was to identify polymorphs of taxifolin prepared...
Taxifolin, also known as dihydroquercetin, possesses several interesting biological properties. The purpose of the study was to identify polymorphs of taxifolin prepared using crystallization in different solvents. Data from X-ray powder diffraction, differential scanning calorimetry, and thermogravimetry enabled us to detect six different crystalline phases for taxifolin. Besides the already known fully hydrated phase, one partially hydrated phase, one monohydrated phase, two anhydrous polymorphs, and one probably solvated phase were obtained. The unit cell parameters were defined for three of them, while one anhydrous polymorph was fully structurally characterized by X-ray powder diffraction data. Scanning electron microscopy and hot stage microscopy were also employed to characterize the crystallized taxifolin powders. The hydrate and anhydrous forms showed remarkable stability in drastic storage conditions, and their solubility was deeply evaluated. The anhydrous form converted into the hydrate form during the equilibrium solubility study and taxifolin equilibrium solubility was about 1.2 mg/mL. The hydrate taxifolin intrinsic dissolution rate was 56.4 μg cm min. Using Wood's apparatus, it was not possible to determine the intrinsic dissolution rate of anhydrous taxifolin that is expected to solubilize more rapidly than the hydrate form. In view of its high stability, its use can be hypothesized.
PubMed: 34575404
DOI: 10.3390/pharmaceutics13091328 -
Molecules (Basel, Switzerland) May 2021The present work is a concrete example of how physico-chemical studies, if performed in depth, are crucial to understand the behavior of pharmaceutical solids and...
The present work is a concrete example of how physico-chemical studies, if performed in depth, are crucial to understand the behavior of pharmaceutical solids and constitute a solid basis for the control of the reproducibility of the industrial batches. In particular, a deep study of the thermal behavior of glipizide, a hypoglycemic drug, was carried out with the aim of clarifying whether the recognition of its polymorphic forms can really be done on the basis of the endothermic peak that the literature studies attribute to the melting of the compound. A number of analytical techniques were used: thermal techniques (DSC, TGA), X-ray powder diffraction (XRPD), FT-IR spectroscopy and scanning electron microscopy (SEM). Great attention was paid to the experimental design and to the interpretation of the combined results obtained by all these techniques. We proved that the attribution of the endothermic peak shown by glipizide to its melting was actually wrong. The DSC peak is no doubt triggered by a decomposition process that involves gas evolution (cyclohexanamine and carbon dioxide) and formation of 5-methyl--[2-(4-sulphamoylphenyl) ethyl] pyrazine-2-carboxamide, which remains as decomposition residue. Thermal treatments properly designed and the combined use of DSC with FT-IR and XRPD led to identifying a new polymorphic form of 5-methyl--[2-(4-sulphamoylphenyl) ethyl] pyrazine-2-carboxamide, which is obtained by crystallization from the melt. Hence, our results put into evidence that the check of the polymorphic form of glipizide cannot be based on the temperature values of the DSC peak, since such a peak is due to a decomposition process whose Tonset value is strongly affected by the particle size. Kinetic studies of the decomposition process show the high stability of solid glipizide at room temperature.
Topics: Calorimetry, Differential Scanning; Glipizide; Hypoglycemic Agents; Microscopy, Electron, Scanning; Powder Diffraction; Spectroscopy, Fourier Transform Infrared; Thermogravimetry
PubMed: 34073973
DOI: 10.3390/molecules26113142 -
The Review of Scientific Instruments Jan 2021An ultrafast x-ray powder diffraction setup for laser-driven dynamic compression has been developed at the LULI2000 laser facility. X-ray diffraction is performed in...
An ultrafast x-ray powder diffraction setup for laser-driven dynamic compression has been developed at the LULI2000 laser facility. X-ray diffraction is performed in reflection geometry from a quasi-monochromatic laser-generated plasma x-ray source. In comparison to a transmission geometry setup, this configuration allows us to probe only a small portion of the compressed sample, as well as to shield the detectors against the x-rays generated by the laser-plasma interaction on the front side of the target. Thus, this new platform facilitates probing of spatially and temporarily uniform thermodynamic conditions and enables us to study samples of a large range of atomic numbers, thicknesses, and compression dynamics. As a proof-of-concept, we report direct structural measurements of the bcc-hcp transition both in shock and ramp-compressed polycrystalline iron with diffraction signals recorded between 2θ ∼ 30° and ∼150°. In parallel, the pressure and temperature history of probed samples is measured by rear-side visible diagnostics (velocimetry and pyrometry).
PubMed: 33514214
DOI: 10.1063/5.0020261 -
Scientific Reports Oct 2020CaGaO was successfully synthesized using a wet chemistry technique to promote the homogenous mixing of the Ca and Ga cations. Rietveld refinements on X-ray and neutron...
CaGaO was successfully synthesized using a wet chemistry technique to promote the homogenous mixing of the Ca and Ga cations. Rietveld refinements on X-ray and neutron powder diffraction data confirm that the compound is isostructural to CaAlO however, with a significantly larger lattice parameter allowing for the cages that result from the framework arrangement to expand. In naturally occurring CaAlO, the mineral mayenite, these cages are occupied by O anions, however, experimental studies exchanging the O anions with other anions has led to a host of applications, depending on the caged anion. The functional nature of the structure, where framework distortions coupled with cage occupants, are correlated to electronic band structure and modifications to the framework could lead to interesting physical properties. The phase evolution was tracked using thermogravimetric analysis and high temperature X-ray diffraction and showed a lower formation temperature for the CaGaO analogue compared to CaAlO synthesized using the same wet chemistry technique. Analyzing both X-ray and neutron powder diffraction using the Rietveld method with two different starting models results in one structural model, with one Ca position and the caged O on a 24d special position, being preferred.
PubMed: 33004913
DOI: 10.1038/s41598-020-73311-w -
Journal of Applied Crystallography Oct 2023The general-purpose powder diffractometer beamline (BL2-1) at the Stanford Synchrotron Radiation Lightsource (SSRL) is described. The evolution of design and performance...
The general-purpose powder diffractometer beamline (BL2-1) at the Stanford Synchrotron Radiation Lightsource (SSRL) is described. The evolution of design and performance of BL2-1 are presented, in addition to current operating specifications, applications and measurement capabilities. Recent developments involve a robotic sample changer enabling high-throughput X-ray diffraction measurements, applicable to mail-in and remote operations. and capabilities to measure samples with different form factors ( capillary, flat plate or thin film, and transmission) and under variable experimental conditions are discussed. Several example datasets and accompanying Rietveld refinements are presented.
PubMed: 37791352
DOI: 10.1107/S1600576723007148 -
ACS Applied Materials & Interfaces Sep 2019High-temperature thermochromic materials are poorly explored in fundamental research, let alone applied research, although these materials may be used as low-cost,...
High-temperature thermochromic materials are poorly explored in fundamental research, let alone applied research, although these materials may be used as low-cost, intuitively usable sensing materials in an industrial environment. Yet, only few of these materials have been described systematically. We describe a series of yttrium-substituted bismuth oxides (BiY)O (0.05 ≤ ≤ 0.25) that show thermochromic behavior with a color change from yellow at low temperatures to various brown hues at high temperatures. The compounds were analyzed between 293 and 1050 K by X-ray powder diffraction, UV/vis spectroscopy, and differential scanning calorimetry. A combination of derived absorption spectral fitting and Tauc methods was applied to determine the band gap energies and band gap types from the diffuse UV/vis spectra, respectively. Two types of materials were found: one with = 0.05 that exhibits the tetragonal β-phase at room temperature, and the defect fluorite-type cubic δ-phase at temperatures above 920 K. This phase showed a reversible, gradual color change upon heating, followed by an abrupt color change at the phase-transformation temperature. The second type of material had higher yttrium contents ( > 0.10); these samples were cubic at room temperature and showed a continuous color change upon heating and cooling. In contrast to the material with = 0.05, these latter phases show a reduced cycle stability and were gradually annealed to the hexagonal phase-I. The samples with = 0.10 provided a mixture of the β- and δ-phases, showing both, the reversible behavior for the β- to δ-phase transition and the irreversible behavior concerning the β-phase. This points the way toward smart materials that can not only sense the actual thermal stress but also monitor cumulative thermal stresses over a certain material lifetime.
PubMed: 31415152
DOI: 10.1021/acsami.9b11450 -
Pharmaceutical Research Dec 2023To synthesize and characterize new cocrystals of berberine chloride (BCl) for potential pharmaceutical tablet formulation.
PURPOSE
To synthesize and characterize new cocrystals of berberine chloride (BCl) for potential pharmaceutical tablet formulation.
METHODS
Solutions of BCl with each of three selected cocrystal formers, catechol (CAT), resorcinol (RES), and hydroquinone (HYQ) were slowly evaporated at room temperature to obtain crystals. Crystal structures were solved using single crystal X-ray diffraction. Bulk powders were characterized by powder X-ray diffraction, thermogravimetric-differential scanning calorimetry, FTIR, dynamic moisture sorption, and dissolution (both intrinsic and powder).
RESULTS
Single crystal structures confirmed the formation of cocrystals with all three coformers, which revealed various intermolecular interactions that stabilized crystal lattices, including O-H···Cl hydrogen bonds. All three cocrystals exhibited better stability against high humidity (up to 95% relative humidity) at 25 ℃ and higher intrinsic and powder dissolution rates than BCl.
CONCLUSION
The enhanced pharmaceutical properties of all three cocrystals, as compared to BCl, further contribute to the existing evidence that confirms the beneficial role of cocrystallization in facilitating drug development. These new cocrystals expand the structure landscape of BCl solid forms, which is important for future analysis to establish a reliable relationship between crystal structure and pharmaceutical properties.
Topics: Berberine; Chlorides; Crystallization; Powder Diffraction; Powders; Solubility; X-Ray Diffraction; Calorimetry, Differential Scanning
PubMed: 37226026
DOI: 10.1007/s11095-023-03533-w -
Acta Crystallographica Section B,... Dec 2023The structure of (R)-rasagiline mesylate [(R)-RasH·Mes], an active pharmaceutical ingredient used to treat Parkinson's disease, is presented. The structure was...
Hydrogen bonding patterns and C-H...π interactions in the structure of the antiparkinsonian drug (R)-rasagiline mesylate determined using laboratory and synchrotron X-ray powder diffraction data.
The structure of (R)-rasagiline mesylate [(R)-RasH·Mes], an active pharmaceutical ingredient used to treat Parkinson's disease, is presented. The structure was determined from laboratory and synchrotron powder diffraction data, refined using the Rietveld method, and validated and optimized using dispersion-corrected DFT calculations. The unit-cell parameters obtained in both experiments are in good agreement and the refinement with both datasets converged to good agreement factors. The final parameters obtained from laboratory data were a = 5.4905 (8), b = 6.536 (2), c = 38.953 (3) Å, V = 1398.0 (4) Å and from synchrotron powder data were a = 5.487530 (10) Å, b = 6.528939 (12) Å, c = 38.94313 (9) Å, V = 1395.245 (5) Å with Z = 4 and space group P222. Preferred orientation was properly accounted for using the synchrotron radiation data, leading to a March-Dollase parameter of 1.140 (1) instead of the 0.642 (1) value obtained from laboratory data. In the structure, (R)-RasH moieties form layers parallel to the ab plane connected by mesylate ions through N-H...O and C-H...O hydrogen bonds. These layers stack along the c axis and are further connected by C-H...π interactions. Hirshfeld surface analysis and fingerprint plot calculations indicate that the main interactions are: H...H (50.9%), H...C/C...H (27.1%) and H...O/O...H (21.1%).
PubMed: 37820013
DOI: 10.1107/S2052520623007758 -
Pharmaceutics Nov 2022The aim of this study was to improve the physicochemical properties and oral bioavailability of dasatinib (DST) by the amorphous solid dispersion (ASD) approach using...
The aim of this study was to improve the physicochemical properties and oral bioavailability of dasatinib (DST) by the amorphous solid dispersion (ASD) approach using cellulose acetate butyrate (CAB) as a carrier. Various formulations of ASD (DST:CAB 1:1 to 1:5) were prepared by the solvent evaporation method. ASDs were characterized for physicochemical attributes, stability and pharmacokinetics. Scanning electron microscopy, Fourier transformed infrared, X-ray powder diffraction, and differential scanning calorimetry confirmed the transformation of the crystalline drug into amorphous phase. ASD formation resulted in a 3.7−4.9 fold increase in dissolution compared to DST or physical mixture. The ASDs formulation exhibited relative stability against transformation from the unstable amorphous phase to a stable crystalline phase that was indicated by spectral and X-ray powder diffraction data, and insignificant (p > 0.05) decrease in dissolution. Tmax, Cmax and AUC0-∞ of ASD were 4.3-fold faster and 2.0 and 1.5 fold higher than the corresponding physical mixture. In conclusion, the ASD of DST significantly improved dissolution and oral bioavailability which may be translated into a reduction in dose and adverse events.
PubMed: 36432641
DOI: 10.3390/pharmaceutics14112450 -
Materials (Basel, Switzerland) Jul 2021Nano-porous silicon (NPS) powder synthesis is performed by means of a combination of the ultra-sonication technique and the alkali chemical etching process, starting...
Nano-porous silicon (NPS) powder synthesis is performed by means of a combination of the ultra-sonication technique and the alkali chemical etching process, starting with a commercial silicon powder. Various characterization techniques {X-ray powder diffraction, transmission electron microscopy, Fourier Transform Infrared spectrum, and positron annihilation lifetime spectroscopy} are used for the description of the product's properties. The NPS product is a new environmentally friendly material used as an adsorbent agent for the acidic azo-dye, Congo red dye. The structural and free volume changes in NPS powder are probed using positron annihilation lifetime (PALS) and positron annihilation Doppler broadening (PADB) techniques. In addition, the mean free volume (VF), as well as fractional free volume (Fv), are also studied via the PALS results. Additionally, the PADB provides a clear relationship between the core and valence electrons changes, and, in addition, the number of defect types present in the synthesized samples. The most effective parameter that affects the dye removal process is the contact time value; the best time for dye removal is 5 min. Additionally, the best value of the CR adsorption capacity by NPS powder is 2665.3 mg/g at 100 mg/L as the initial CR concentration, with an adsorption time of 30 min, without no impact from temperature and pH. So, 5 min is the enough time for the elimination of 82.12% of the 30 mg/L initial concentration of CR. This study expresses the new discovery of a cheap and safe material, in addition to being environmentally friendly, without resorting to any chemical additives or heat treatments.
PubMed: 34361446
DOI: 10.3390/ma14154252