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Raj Suryanarayanan - One of the best experts on this subject based on the ideXlab platform.

  • applications of synchrotron Powder x ray Diffractometry in drug substance and drug product characterization
    Trends in Analytical Chemistry, 2021
    Co-Authors: Bhushan Munjal, Raj Suryanarayanan
    Abstract:

    Abstract While X-Ray Powder Diffractometry (XRD) is a powerful technique for characterizing crystalline phases, the sensitivity of the laboratory instruments can be a serious limitation. The use of synchrotron radiation has substantially enhanced its utility and synchrotron XRD (SXRD) has emerged as a powerful tool for analyzing pharmaceutical materials. The numerous applications of SXRD in both drug substance and drug product characterization have been comprehensively summarized. The applications are categorized into three areas: 1) Detection, characterization and quantification of multiple physical forms of the API in the DS. 2) Similar investigations in complex and multicomponent drug products. 3) Characterization and quantification of phase transformations during processing and storage. Thus, SXRD based studies have assisted pharmaceutical development by enhancing the understanding of mechanisms and kinetics of phase transformations during various pharmaceutical unit operations including crystallization and freeze drying. Subtle and nuanced information has been obtained during DP dissolution and long-term stability studies.

  • a refined phase diagram of the tert butanol water system and implications on lyophilization process optimization of pharmaceuticals
    Physical Chemistry Chemical Physics, 2020
    Co-Authors: Bakul Bhatnagar, Jayesh Sonje, Evgenyi Y Shalaev, Susan W H Martin, Dirk L Teagarden, Raj Suryanarayanan
    Abstract:

    While water is the solvent of choice for the lyophilization of pharmaceuticals, tert-butyl alcohol (TBA) along with water can confer several advantages including increased solubility of hydrophobic drugs, decreased drying time, improved product stability and reconstitution characteristics. The goal of this work was to generate the phase diagram and determine the eutectic temperature and composition in the “water rich” region (0.0 to 25.0% w/w TBA) of TBA–water mixtures. Solutions of different compositions were frozen and characterized by low temperature differential scanning calorimetry and Powder X-Ray Diffractometry (XRD). The thermal events observed during warming, and their characterization by XRD, enabled the generation of phase boundaries as well as the eutectic temperature and composition. While TBA crystallized as a dihydrate in frozen solutions, on heating, the dihydrate transformed to a heptahydrate. TBA heptahydrate and ice (22.5% w/w TBA) formed a eutectic at ∼−8 °C.

  • Role of Coformer and Excipient Properties on the Solid-State Stability of Theophylline Cocrystals
    2019
    Co-Authors: Sampada Koranne, Joseph F. Krzyzaniak, Suman Luthra, Kapildev K. Arora, Raj Suryanarayanan
    Abstract:

    The stability of theophylline cocrystals composed of acidic (glutaric acid), basic (isonicotinamide), or neutral (benzamide) coformers was evaluated in the presence of several excipients. Tablets of theophylline-glutaric acid (TG) and theophylline-isonicotinamide (TINT) cocrystals were stable “as is” (no excipient) after storage at 40 °C/75% RH for 1 week. However, TG and TINT cocrystals dissociated rapidly in the presence of basic and acidic excipients, respectively. The dissociation reaction was water-mediated, and theophylline, the reaction product, was identified by Powder X-Ray Diffractometry. In the case of theophylline-benzamide cocrystal, storage of tablets with and without excipients at 40 °C/75% RH for 1 week resulted in a cocrystal polymorphic transformation. Thus, the potential for excipient-induced cocrystal dissociation exists for cocrystals composed of acidic and basic coformers. Moreover, if the coformer renders the cocrystal highly water-soluble, even in the presence of neutral excipients, there is a propensity for dissociation

  • correlation between molecular mobility and physical stability in pharmaceutical glasses
    Molecular Pharmaceutics, 2016
    Co-Authors: Mehak Mehta, Vishard Ragoonanan, Gregory B Mckenna, Raj Suryanarayanan
    Abstract:

    We investigated a possible correlation between molecular mobility and physical stability in glassy celecoxib and indomethacin and identified the specific mobility mode responsible for physical instability (crystallization). In the glassy state, because the structural relaxation times are very long, the measurement was enabled by time domain dielectric spectroscopy. However, the local motions in the glassy state were characterized by frequency domain dielectric spectroscopy. Isothermal crystallization was monitored by Powder X-Ray Diffractometry using either a laboratory source (supercooled state) or synchrotron source (glassy state). Structural (α) relaxation time correlated well with characteristic crystallization time in the supercooled state. On the other hand, a stronger correlation was observed between the Johari–Goldstein (β) relaxation time and physical instability in the glassy state but not with structural relaxation time. These results suggest that Johari–Goldstein relaxation is a potential pred...

  • the role of drug polymer hydrogen bonding interactions on the molecular mobility and physical stability of nifedipine solid dispersions
    Molecular Pharmaceutics, 2015
    Co-Authors: Khushboo Kothari, Vishard Ragoonanan, Raj Suryanarayanan
    Abstract:

    We investigated the influence of drug–polymer hydrogen bonding interactions on molecular mobility and the physical stability in solid dispersions of nifedipine with each of the polymers polyvinylpyrrolidone (PVP), hydroxypropylmethyl cellulose (HPMCAS), and poly(acrylic acid) (PAA). The drug–polymer interactions were monitored by FT-IR spectroscopy, the molecular mobility was characterized using broadband dielectric spectroscopy, and the crystallization kinetics was evaluated by Powder X-Ray Diffractometry. The strength of drug–polymer hydrogen bonding, the structural relaxation time, and the crystallization kinetics were rank ordered as PVP > HPMCAS > PAA. At a fixed polymer concentration, the fraction of the drug bonded to the polymer was the highest with PVP. Addition of 20% w/w polymer resulted in ∼65-fold increase in the relaxation time in the PVP dispersion and only ∼5-fold increase in HPMCAS dispersion. In the PAA dispersions, there was no evidence of drug–polymer interactions and the polymer addit...

Xingwang Zhang - One of the best experts on this subject based on the ideXlab platform.

  • design and evaluation of injectable niclosamide nanocrystals prepared by wet media milling technique
    Drug Development and Industrial Pharmacy, 2015
    Co-Authors: Xingwang Zhang, Tianpeng Zhang, Huan Wang
    Abstract:

    Niclosamide is an anthelmintic drug that also demonstrates great potential in fighting against cancers. However, parenteral delivery of niclosamide is challenged due to its insoluble property. This study aimed to develop an injectable formulation for niclosamide using nanocrystals. Niclosamide nanocrystals were prepared by wet media milling technique and characterized by electronic microscopes, differential scanning calorimetry, Powder X-Ray Diffractometry and drug release, etc. The resulting nanocrystals using Tween 80 as the stabilizer were approximately 235 nm in particle size and showed a satisfactory stability. Pharmacokinetic studies revealed that there was no significant difference in plasma concentration-time profiles between nanocrystals and the control formulation (i.e. drug solution). By contrast, a significant difference in tissue distribution was observed at 2 h. Further, niclosamide nanocrystals presented a comparable antitumor effect to the drug solution against EC9076 cell line. We concluded that the nanocrystal formulation with solution-like behaviors should be a promising choice for intravenous delivery of niclosamide.

  • physical characterization of meloxicam β cyclodextrin inclusion complex pellets prepared by a fluid bed coating method
    Particuology, 2009
    Co-Authors: Xingwang Zhang, Jie Lai, Zongning Yin
    Abstract:

    Abstract Meloxicam-β-cyclodextrin (ME-β-CD) inclusion complex was prepared by a fluid-bed coating technique upon solvent removal and simultaneous depositing onto the surface of nonpareil pellets and using PVP K30 as a binding agent to facilitate good coating. The resultant pellets were spherical and intact in shape with good flowability and friability. SEM analysis showed that the pellets were smooth and had a tightly coated inclusion complex layer. In vitro dissolution of the inclusion complex pellets in pH 7.4 phosphate buffer was dramatically enhanced at an ME/CD ratio of 1/1. DSC and Powder X-Ray Diffractometry proved the absence of crystallinity in the ME/CD inclusion complexes. Moreover, Fourier transform-infrared spectrometry together with Raman spectrometry indicated that the thiazole ring of ME was possibly included in the cavity of β-CD.

  • physical characterization of lansoprazole pvp solid dispersion prepared by fluid bed coating technique
    Powder Technology, 2008
    Co-Authors: Xingwang Zhang, Ningyun Sun, Tianzheng Guan
    Abstract:

    The aim of this study was to characterize lansoprazole (LSP) /PVP solid dispersion prepared by a fluid-bed coating technique. In vitro dissolution test in pH 7.4 phosphate buffer indicated that the dissolution rate was dramatically enhanced even at an LSP/PVP ratio of 1/1.75 or with more PVP. DSC and Powder X-Ray Diffractometry proved the absence of crystallinity in LSP/PVP solid dispersion at a ratio of 1/2 or with more PVP. However, at an LSP/PVP ratio of 1/1, the LSP melting and decomposition peaks could be observed by DSC indicating presence of LSP crystalline in LSP/PVP solid dispersion. The FTIR spectrometry indicated formation of hydrogen bond between LSP and PVP.

  • in vitro evaluation and pharmacokinetics in dogs of solid dispersion pellets containing silybum marianum extract prepared by fluid bed coating
    Planta Medica, 2008
    Co-Authors: Ningyun Sun, Xingwang Zhang
    Abstract:

    The solid dispersion of a poorly water-soluble Silybum marianum extract (SME) was prepared by a one-step fluid-bed coating technique depositing onto non-pareil pellets. In vitro evaluation indicated that this technique was highly efficient and reproducible producing pellets with acceptable appearance, flowability, friability, uniformity of drug content and enhanced dissolution. Physical characterization by DSC, Powder X-Ray Diffractometry and FT-IR suggested the formation of a solid dispersion and possible interaction between PVP and the flavonolignans. Stress testing showed that the drug content and dissolution profiles of the SME solid dispersion pellets were sensitive to heat and humidity, while they are not affected under accelerated and long-term testing conditions. The relative bioavailability of solid dispersion pellets in dogs based on quantification of silibinin was about five-fold that of the SME suspension confirming enhanced oral bioavailability. It was concluded that the solid dispersion pellets prepared by fluid-bed coating showed favorable in vitro characteristics and enhanced oral bioavailability.

Woosuck Shi - One of the best experts on this subject based on the ideXlab platform.

  • dilatometry and high temperature x ray Diffractometry study of la0 6sr0 4ti0 1fe0 9o3 δ and la0 6sr0 4ti0 3fe0 7o3 δ oxygen permeable membranes
    Solid State Ionics, 2010
    Co-Authors: Yosuke Takahashi, Takehiro Suzuki, Akihiro Kawahara, Yasunori Ando, Masayoshi Hirano, Woosuck Shi
    Abstract:

    Abstract The thermal expansion behavior of La 0.6 Sr 0.4 Ti 1 − x Fe x O 3 − δ (x = 0.7 and 0.9) was investigated by dilatometry and in situ Powder X-Ray Diffractometry at 25 and 1000 °C under controlled oxygen partial pressures in air and at reducing atmosphere, P O2  = 0.21 and 1 × 10 − 20  atm, respectively. The sintered samples of x = 0.7 and 0.9 showed positive thermal expansions, i.e., 12.4 and 14.4 × 10 − 6  K − 1 , respectively, in air up to 1000 °C, and also larger expansions at lower partial oxygen pressures, with a linear thermal expansion ratio factor of 0.10 and 0.40%. The change in the crystal lattice parameters analyzed by XRD Rietveld refinement showed that the crystal lattice volume increased with an increase in temperature and a decrease P O2 . The linear thermal expansion rates estimated from volume change of the XRD data for the oxides of x = 0.7 and 0.9, were 0.13 and 0.27%, which corresponds to those of estimated from the dilatometry.

Hideo Toraya - One of the best experts on this subject based on the ideXlab platform.

  • crystallographic data of a new phase of dicalcium silicate
    Journal of the American Ceramic Society, 2005
    Co-Authors: Makoto Miyazaki, Satoru Yamazaki, Kaori Sasaki, Hideki Ishida, Hideo Toraya
    Abstract:

    Unit-cell parameters and the space group of a new phase of dicalcium silicate (Ca2SiO4) were determined by using Powder X-Ray Diffractometry and selected-area electron diffraction techniques. This phase could be synthesized via the dissociation of hydrothermally synthesized alpha-Ca2(SiO4H)OH at temperatures of ∼500°-920°C. Crystallographic data for the sample synthesized at 600°C were as follows: Ca2SiO4, monoclinic; P21/c space group; lattice parameters of a= 0.82147(9) nm, b= 0.9808(1) nm, c= 0.9741(1) nm, and β= 94.642(7)°; cell volume (V) of 0.7857(1) nm3; Z= 8 (where Z is the number of chemical formula units in a unit cell); and a density of 2.91 g/cm3. The crystallographic data for samples synthesized at 800°C had slightly different unit-cell parameters of a= 0.82124(6) nm, b= 0.97348(7) nm, c= 0.97935(7) nm, β= 94.831(5)°, and V= 0.7849(1) nm3. Structural relationships of the new phase with the other dicalcium silicates are discussed.

  • deconvolution of the instrumental functions in Powder x ray Diffractometry
    Journal of Applied Crystallography, 2002
    Co-Authors: Takashi Ida, Hideo Toraya
    Abstract:

    A novel method to deconvolute the instrumental aberration functions from the experimental Powder X-Ray data has been developed. The method is based on the combination of scale transformation, interpolation of data and fast Fourier transformation. The effects of axial divergence, flat specimen, sample transparency and spectroscopic profile of the source X-Ray are eliminated from the entire observed diffraction pattern in three-step operations. The errors in the deconvoluted data propagated from the statistical uncertainty in the source data are approximated by the reciprocal of the square root of the correlation between the reciprocal of the variance in the source data and the squared instrumental function. The deconvolution of the instrumental aberration functions enables automatic correction of peak shift and line broadening, and supplies narrow and symmetric peak profiles for a well crystallized sample, which can be fitted by a simple model function. It will be useful in preparatory data processing for precise line profile analysis, accurate determination of lattice parameters and whole pattern fitting for crystal structure analysis.

David J W Grant - One of the best experts on this subject based on the ideXlab platform.

  • local structure in amorphous phases of piroxicam from Powder x ray Diffractometry
    Crystal Growth & Design, 2005
    Co-Authors: Agam R Sheth, Simon Bates, Francis X Muller, David J W Grant
    Abstract:

    The local structures of amorphous phases of piroxicam were studied to explain differences in their recrystallization behavior, which we reported earlier (Sheth, A. R.; Bates, S.; Muller, F. X.; Grant, D. J. W. Polymorphism in piroxicam. Cryst. Growth Des., in press). The differences between the structures of form I (PI) at 25 and at 160 °C are consistent with anisotropic thermal expansion (αx = 2.85 × 10-5 K-1, αy = 1.96 × 10-5 K-1, αz = 5.26 × 10-6 K-1, volume thermal expansivity of the unit cell = 4.92 × 10-5 K-1, increase in unit cell volume = 2.01%). Cryogenic grinding was employed to produce the respective amorphous forms, PAI from PI and PAII from PII. Pairwise distribution function (PDF) transforms were utilized to compare atom to atom correlations in PAI and PAII and to understand differences in their recrystallization behavior on the basis of their local structure. PDF transforms showed that PAI and PAII are types of amorphous material, which may be termed random ordered network (RON) amorphous. ...

  • neotame anhydrate polymorphs ii quantitation and relative physical stability
    Pharmaceutical Research, 2002
    Co-Authors: Zedong Dong, Eric J Munson, Steve A Schroeder, Indra Prakash, David J W Grant
    Abstract:

    Purpose. To study the relative thermodynamic and kinetic stabilities of neotame anhydrate polymorphs A, D, F, and G, and to develop a quantitative method for analyzing polymorphic mixtures of A and G by Powder X-Ray Diffractometry (PXRD).

  • dehydration kinetics of neotame monohydrate
    Journal of Pharmaceutical Sciences, 2002
    Co-Authors: Zedong Dong, Eric J Munson, Steve A Schroeder, Jonathon S Salsbury, Deliang Zhou, Charles A Wight, Sergey Vyazovkin, Indra Prakash, David J W Grant
    Abstract:

    The dehydration of neotame monohydrate was monitored at various temperatures by differential scanning calorimetry (DSC), thermogravimetry (TGA), hot-stage microscopy (HSM), Powder X-Ray Diffractometry (PXRD), and 13 C solid-state nuclear magnetic resonance (SSNMR) spectroscopy. This work emphasizes kinetic analysis of isothermal TGA data by fitting to various solid-state reaction models and by model-free kinetic treatment. The dehydration of neotame monohydrate follows the kinetics of a two-dimensional phase boundary reaction (R2) at 40-508C with an activation energy of 75 � 9 kJ/mol, agreeing well with 60-80 kJ/mol from model-free kinetics. At a low heating rate in DSC and TGA, neotame monohydrate undergoes dehydration to produce anhydrate Form E, which then converts to anhydrate Form A, followed by the melting of A. Neotame monohydrate under dry nitrogen purge at 50 mL/min undergoes partial isothermal dehydration at 508C to produce neotame anhydrate Form A. When neotame monohydrate is heated very slowly from 50 to 65- 708C over 24 h, pure Form A is obtained. 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:1423-1431, 2002

  • Crystallization and Transitions of Sulfamerazine Polymorphs
    Journal of pharmaceutical sciences, 2002
    Co-Authors: Geoff G. Z. Zhang, Eric J Munson, Mark T. Zell, R. Todd Burkhardt, David J W Grant
    Abstract:

    A bulk Powder of sulfamerazine polymorph II in a narrow distribution of particle size was prepared for the first time. The two known sulfamerazine polymorphs, I and II, were physically characterized by optical microscopy, Powder X-Ray Diffractometry, differential scanning calorimetry, carbon-13 solid-state nuclear magnetic resonance spectroscopy, and measurements of aqueous solubility and density. The thermodynamics and kinetics of the transition between the polymorphs was examined under various pharmaceutically relevant conditions, such as heating, cooling, milling, compaction, and contact with solvents. The two polymorphs were found to be enantiotropes with slow kinetics of interconversion. The thermodynamic transition temperature lies between 51 and 54°C, with polymorph II stable at lower temperatures. Ostwald's Rule of Stages explains the crystallization of the polymorphs from various solvents and may account for the delay in the discovery of polymorph II. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:1089–1100, 2002