Solid state characterization and crystal structure from X-ray powder diffraction of two polymorphic forms of ranitidine base.

Ranitidine hydrochloride (RAN-HCl), a known anti-ulcer drug, is the product of reaction between HCl and ranitidine base (RAN-B). RAN-HCl has been extensively studied; however this is not the case of the RAN-B. The solid state characterization of RAN-B polymorphs has been carried out using different analytical techniques (microscopy, thermal analysis, Fourier transform infrared spectrometry in the attenuated total reflection mode, (13)C-CPMAS-NMR spectroscopy and X-ray powder diffraction).

Hydrogen-bonding patterns in rac-1-acetyl-5-methyl-2-thioxoimidazolidin-4-one.

In the title compound, C(6)H(8)N(2)O(2)S, also known as N-acetyl-2-thiohydantoin-alanine, the molecules are joined by N-H...

Phase characterization of indomethacin in binary solid dispersions with PVP VA64 or Myrj 52.

In the present study the properties of binary solid dispersions made up of PVP VA64, Myrj 52 and indomethacin (IMC) are studied and characterized. The solid dispersions were prepared by dissolving the materials in dichloromethane, followed by solvent evaporation under reduced pressure at 55 degrees C in a rotavapor. Binary solid dispersions were characterized by standard and modulated temperature differential scanning calorimetry (MTDSC), thermogravimetry (TGA) and X-ray powder diffraction (XRPD).

Polymorphism of Alprazolam (Xanax): a review of its crystalline phases and identification, crystallographic characterization, and crystal structure of a new polymorph (form III).

A new polymorphic form of Alprazolam (Xanax), 8-chloro-1-methyl-6-phenyl-4H-[1,2,4]triazolo-[4,3-alpha][1,4]benzodiazepine, C(17)H(13)ClN(4), has been investigated by means of X-ray powder diffraction (XRPD), single crystal X-ray diffraction, and differential scanning calorimetry (DSC). This polymorphic form (form III) was obtained during DSC experiments after the exothermic recrystallization of the melt of form I. The crystal unit cell dimensions for form III were determined from diffractometer methods.

Characterization of physico-chemical properties and pharmaceutical performance of sucrose co-freeze-dried solid nanoparticulate powders of the anti-HIV agent loviride prepared by media milling.

In order to improve the dissolution and absorption properties of loviride, a poorly soluble antiviral agent, sucrose co-freeze-dried nanopowders were prepared, characterized and evaluated. Tween 80/poloxamer 188-stabilized nanosuspensions were produced on a laboratory scale using media milling. The milling process was monitored by dynamic light scattering (DLS) and resulted in particles with a mean size of 264+/-14nm and a distribution width of 59+/-6nm after 4h of milling.

Crystal structure of carnidazole form II from synchrotron X-ray powder diffraction: structural comparison with form I, the hydrated form and the low energy conformations in vacuo.

The crystal structure of carnidazole form II, O-methyl [2-(2-methyl-5-nitro-1H-imidazole-1-yl)ethyl]thiocarbamate, has been determined using synchrotron X-ray powder diffraction in combination with simulated annealing and whole profile pattern matching, and refined by the Rietveld method. For structure solution, 12 degrees of freedom were defined: one motion group and six torsions. Form II crystallizes in space group P2(1)/n, Z=4, with unit cell parameters after Rietveld refinement: a=13.

Evaluation of Inutec SP1 as a new carrier in the formulation of solid dispersions for poorly soluble drugs.

Solid dispersions made up of itraconazole and Inutec SP1, a new polymeric surfactant, were prepared by spray drying and hot-stage extrusion. Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD) were used to evaluate the miscibility of the components of the dispersions, and dissolution experiments were performed in simulated gastric fluid without pepsin (SGFsp) to evaluate the pharmaceutical performance of itraconazole from the solid dispersions. DSC analysis showed that the solid dispersions are phase separated systems made up of glassy and crystalline itraconazole and amorphous Inutec SP1.

Salt formation in solid dispersions consisting of polyacrylic acid as a carrier and three basic model compounds resulting in very high glass transition temperatures and constant dissolution properties upon storage.

The purpose of the study was to investigate the suitability of polyacrylic acid (PAA) as a carrier in solid dispersions, with the aim to delay crystallization of basic drugs and improve their dissolution behaviour. The physicochemical properties were investigated in order to link the physical state of some model compounds to their dissolution properties. Loperamide and two structurally related substances were selected as model compounds.

Tribenzylphosphine oxide.

The title compound, (C(6)H(5)CH(2))(3)PO, is an organic tertiary phosphine oxide. The molecule has threefold symmetry, with the P-O bond along the threefold axis. Main dimensions include P-O 1.

Copper(II) complexes of pentadentate 17-membered macrocyclic diamidodiamines with N, O or S as additional donors.

The crystal structures of (2,6-dioxo-1,4,7,11,14-pentaazacycloheptadecanato)copper(II) tetrahydrate, [Cu(C(12)H(23)N(5)O(2))].4H(2)O, (I), (3,16-dioxo-1-oxa-4,8,11,15-tetraazacycloheptadecanato)copper(II) pentahydrate, [Cu(C(12)H(22)N(4)O(3))].5H(2)O, (II), and (3,16-dioxo-1-thia-4,8,11,15-tetraazacycloheptadecanato)copper(II) trihydrate, [Cu(C(12)H(22)N(4)O(2)S)].

Vibrational study of the secondary thioamide function, the intramolecular resonance assisted and intermolecular hydrogen bonding in NN'-hydroxyalkyl dithiooxamides.

The article describes the vibrational characterization of the secondary thioamide formation and especially a spectroscopical interesting study of different types of hydrogen bonding in NN'-dihydroxyalkyldithiooxamides.

Improvement of the dissolution rate of artemisinin by means of supercritical fluid technology and solid dispersions.

The purpose of this study was to enhance the dissolution rate of artemisinin in order to improve the intestinal absorption characteristics. The effect of: (1) micronisation and (2) formation of solid dispersions with PVPK25 was assessed in an in vitro dissolution system [dissolution medium: water (90%), ethanol (10%) and sodium lauryl sulphate (0.1%)].

Vibrational characterization of the peptide bond.

This article describes the complete vibrational analysis of N,N'-dimethyloxamide, CH3HNCOCONHCH3, on basis of the infrared and Raman spectra of four isotopes (H, D, CH3, CD3). Force field calculations on the monomers and multimers (n = 5) combined with solid state spectra in the -196 to +100 degrees C temperature range have been used to obtain a better understanding of the influence of hydrogen bonding on the typical amide fundamentals. The cooperative effect in de series monomer --> multimers --> solid state at decreasing temperatures has been demonstrated.

Mechanism of increased dissolution of diazepam and temazepam from polyethylene glycol 6000 solid dispersions.

Solid dispersion literature, describing the mechanism of dissolution of drug-polyethylene glycol dispersions, still shows some gaps; (A). only few studies include experiments evaluating solid solution formation and the particle size of the drug in the dispersion particles, two factors that can have a profound effect on the dissolution. (B).

Physical stability of solid dispersions of the antiviral agent UC-781 with PEG 6000, Gelucire 44/14 and PVP K30.

This paper describes the physical stability of solid dispersions of UC-781 with PEG 6000, Gelucire 44/14 and PVP K30 prepared by the solvent and melting methods. The concentration of the drug in the solid dispersions ranged from 5 to 80% w/w. The solid dispersions were stored at 4-8 and 25 degrees C (25% RH), then their physicochemical properties were analysed by differential scanning calorimetry (DSC), X-ray powder diffraction and dissolution studies as a function of storage time.

5'-Deoxy congeners of 9-(3-amido-3-deoxy-beta-D-xylofuranosyl)-N(6)-cyclopentyladenine: new adenosine A(1) receptor antagonists and inverse agonists.

The synthesis and structure-activity relationship of N(6)-cyclopentyl-3'-substituted-xylofuranosyladenosine analogues with respect to various adenosine receptors were explored in order to identify selective and potent antagonists and inverse agonists for the adenosine A(1) receptor. In particular, the effects of removal of the 5'-OH group and introduction of selected substituents at the 3'-NH(2) position of 9-(3-amino-3-deoxy-beta-D-xylofuranosyl)-N(6)-cyclopentyladenine were probed. A solid phase-assisted synthetic approach was used to optimize the 3'-amide functionality.

Solid state properties of pure UC-781 and solid dispersions with polyvinylpyrrolidone (PVP K30).

The purpose of this study was to elucidate the physical structure of solid dispersions of the antiviral agent UC-781 (N-[4-chloro-3-(3-methyl-2-butenyloxy)phenyl]-2-methyl-3-furancarbothioamide) with polyvinylpyrrolidone (PVP K30). Solid dispersions were prepared by coevaporating UC-781 with PVP K30 from dichloromethane. The physicochemical properties of the dispersions were evaluated in comparison with the physical mixtures by differential scanning calorimetry (DSC), X-ray powder diffraction, and FT-IR spectroscopy.

The effect of pressure and temperature on the vibrational spectra of different hydrogen bonded systems.

The effect of pressure and temperature on the vibrational spectra of hydrogen bonded systems has been studied on amides, thioamides, carboxylic acids and urea. The compounds under investigation are indicative for the kind of hydrogen bonding changing from pure intermolecular to intramolecular and dimeric forms. The discussion of the temperature dependence on the fundamentals involved in the hydrogen bonding is straightforward but the pressure data are much more complicated and only if the changes in the crystalline state at different pressures are known, we will have a better understanding of the dependence of some fundamentals in the hydrogen bonded systems.

p-Formamidobenzoic acid.

The title compound, C8H7NO3, is an aromatic amide that forms an extensive hydrogen-bond network within the crystal. The crystals were obtained while preparing derivatives of benzoic acid as intermediaries in the synthesis of acridones.

Physical stabilisation of amorphous ketoconazole in solid dispersions with polyvinylpyrrolidone K25.

The glass forming properties of ketoconazole were investigated using differential scanning calorimetry (DSC), by quench cooling liquid ketoconazole from T(m)+10 to 273.1 K, followed by subsequent heating at 5 K/min to T(m)+10 K. It was shown that liquid ketoconazole forms a glass which did not recrystallise following reheating, indicating its stability; T(g) was found to be 317.

Ethyl methyl 1,4-dihydro-4-(3-nitrophenyl)-2, 6-bis(1-piperidylmethyl)pyridine-3,5-dicarboxylate.

In the title compound, C(28)H(38)N(4)O(6), the 4-aryl substituent occupies a pseudo-axial position approximately orthogonal to the plane of the dihydropyridine ring [88.1 (3) degrees ]. The dihydropyridine ring adopts a flattened boat conformation.

O-Isopropyl N-(2-furoyl)thiocarbamate.

The title compound, C(9)H(11)NO(3)S, has crystallographic mirror symmetry, occurs in the thiocarbamate form and is stabilized in an s-cisoid,s-transoid conformation with respect to the C-N-C group. There are two intramolecular hydrogen bonds, one between the H atom of the N-H group and the O atom of the furan ring, and the other between the H atom of the secondary carbon of the isopropyl group and the S atom. The packing of the molecules is assumed to be dictated by van der Waals interactions.

Physicochemical characterization of solid dispersions of the antiviral agent UC-781 with polyethylene glycol 6000 and Gelucire 44/14.

The purpose of this study was to prepare and characterize solid dispersions of the antiviral thiocarboxanilide UC-781 with PEG 6000 and Gelucire 44/14 with the intention of improving its dissolution properties. The solid dispersions were prepared by the fusion method. Evaluation of the properties of the dispersions was performed using dissolution studies, differential scanning calorimetry, Fourier-transform infrared spectroscopy and X-ray powder diffraction.