Effect of texture on the intrinsic dissolution behaviour of acetylsalicylic acid and tolbutamide compacts

2007 ◽  
Vol 40 (5) ◽  
pp. 857-864 ◽  
Author(s):  
Mikko Tenho ◽  
Jaakko Aaltonen ◽  
Paula Heinänen ◽  
Leena Peltonen ◽  
Vesa-Pekka Lehto
Keyword(s):  
Acetylsalicylic Acid ◽  
Random Distribution ◽  
Preferred Orientation ◽  
X Ray Diffraction ◽  
Intrinsic Dissolution ◽  
X Ray ◽  
Dissolution Studies ◽  
Dissolution Properties ◽  
Dissolution Behaviour ◽  
Attachment Energy

Preferred orientation of crystallites,i.e.texture, is a common result when a sample with an irregular habit of particles is compacted to form a tablet. Since texturization alters the random distribution of the crystal planes on the surface of the compacted sample, the dissolution properties of highly texturized tablets could differ from the properties of a tablet with a less preferred orientation. Three batches from both acetylsalicylic acid and tolbutamide were recrystallized using different crystallization parameters to obtain powders with different texturization behaviour. Several X-ray diffraction procedures were used to characterize the texture and other crystallographic properties of the samples. The intrinsic dissolution profiles were measured using the channel flow technique. In addition, the attachment energy of the crystal planes lying on the surface of the compacts was calculated theoretically. The results indicate that the most texturized compacts had a clearly lower intrinsic dissolution rate than the compacts with a lower degree of preferred orientation. By combining the results of the texture measurements with the calculated attachment energy values, the surface energies of the samples could be estimated and the estimated energy values were in agreement with the results of the dissolution studies. Moreover, it was found that by using the results of the texture measurements, the habit of the sample particles can be successfully predicted.

scholarly journals Synthesis of Metforminium Succinate by Melting. Crystal Structure, Thermal, Spectroscopic and Dissolution Properties

2017 ◽  
Vol 61 (3) ◽  
Author(s):  
Eduardo Plata-Vargas ◽  
Cinthia De la Cruz-Hernández ◽  
Alejandro Dorazco-González ◽  
Inés Fuentes-Noriega ◽  
David Morales-Morales ◽  
...  
Keyword(s):  
Sodium Succinate ◽  
Organic Salt ◽  
Metformin Hydrochloride ◽  
X Ray Diffraction ◽  
Melt Mixing ◽  
Intrinsic Dissolution ◽  
X Ray ◽  
Dissolution Properties ◽  
Ft Ir ◽  
Melting Crystal

The reaction by melt mixing at 220 °C of the antihyperglycemic drug metformin hydrochloride <strong>1</strong> with dehydrated sodium succinate yields efficiently the organic salt [MET]<sub>2</sub>[SUC] <strong>2</strong> (H-MET<sup>+</sup>= metforminium and SUC<sup>2-</sup> = succinate). Solid state CPMAS NMR <sup>13</sup>C spectroscopy experiments, powder X-ray diffraction and FT-IR results support the formation of the pharmaceutical salt <strong>2</strong> in good yields. Besides, the charged-assisted hydrogen bonding interactions of type N-H<sup>…-</sup>O(carboxylate) were thoroughly analyzed by single crystal X-Ray diffraction techniques. Thus, the pharmaceutical salt <strong>2</strong> possesses considerable thermal differences when compared to the pure starting reagents. In addition, intrinsic dissolution rate experiments in buffered aqueous solutions at pH= 6.8 showed a sustained-release behavior of the drug in <strong>2</strong> with a constant value of K<sub>int</sub> = 0.885 mg/min * cm<sup>2</sup>.

scholarly journals Synthesis, Characterization, and Intrinsic Dissolution Studies of Drug–Drug Eutectic Solid Forms of Metformin Hydrochloride and Thiazide Diuretics

Pharmaceutics ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1926
Author(s):  
Guadalupe Coyote-Dotor ◽  
José C. Páez-Franco ◽  
Daniel Canseco-González ◽  
Alejandra Núñez-Pineda ◽  
Alejandro Dorazco-González ◽  
...  
Keyword(s):  
Solid State Nmr ◽  
Metformin Hydrochloride ◽  
Thiazide Diuretics ◽  
X Ray Diffraction ◽  
Spectroscopy Analysis ◽  
Intrinsic Dissolution ◽  
X Ray ◽  
Dissolution Properties ◽  
Binary Eutectic

The mechanochemical synthesis of drug–drug solid forms containing metformin hydrochloride (MET·HCl) and thiazide diuretics hydrochlorothiazide (HTZ) or chlorothiazide (CTZ) is reported. Characterization of these new systems indicates formation of binary eutectic conglomerates, i.e., drug–drug eutectic solids (DDESs). Further analysis by construction of binary diagrams (DSC screening) exhibited the characteristic V-shaped form indicating formation of DDESs in both cases. These new DDESs were further characterized by different techniques, including thermal analysis (DSC), solid state NMR spectroscopy (SSNMR), powder X-ray diffraction (PXRD) and scanning electron microscopy–energy dispersive X-ray spectroscopy analysis (SEM–EDS). In addition, intrinsic dissolution rate experiments and solubility assays were performed. In the case of MET·HCl-HTZ (χMET·HCl = 0.66), we observed a slight enhancement in the dissolution properties compared with pure HTZ (1.21-fold). The same analysis for the solid forms of MET·HCl-CTZ (χMET·HCl = 0.33 and 0.5) showed an enhancement in the dissolved amount of CTZ accompanied by a slight improvement in solubility. From these dissolution profiles and saturation solubility studies and by comparing the thermodynamic parameters (ΔHfus and ΔSfus) of the pure drugs with these new solid forms, it can be observed that there was a limited modification in these properties, not modifying the free energy of the solution (ΔG) and thus not allowing an improvement in the dissolution and solubility properties of these solid forms.

NbN Thin Film of Alternating Textures

2017 ◽  
Vol 898 ◽  
pp. 1431-1437
Author(s):  
Hong Yang Shao ◽  
Kan Zhang ◽  
Yi Dan Zhang ◽  
Mao Wen ◽  
Wei Tao Zheng
Keyword(s):  
Deposition Time ◽  
Peak Position ◽  
Preferred Orientation ◽  
Intrinsic Stress ◽  
Competitive Growth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Orientation Distributions ◽  
Different Thickness ◽  
Deposited Films

The δ-NbN thin films with different thickness have been prepared by reactive magnetron sputtering at different deposition time and exhibited alternating textures between (111) and (200) orientations as a function of thickness. In addition, the grain size, peak position, morphology, residual stress and orientation distributions of the deposited films were explored by X-ray diffraction, low-angel X-ray reflectivity, scanning electron microscopy and surface profiler. The film deposited at 300 s showed a (111) preferred orientation, changing to (200) preferred orientation at 600 s, and exhibited alternating textures between (111) and (200) preferred orientations. With further increasing deposition time, in which (200) peak position and the full width at half maximum of (111) peak also displayed a trend of alternating variation with varying deposition time. The intrinsic stress for δ-NbN films calculated by Stoney equation alternately changed with alternating textures, in which (111) orientation always takes place at relatively high intrinsic stress state and vice versa. Meanwhile, the film with (111) preferred orientation showed higher density than (200) preferred orientation. The film deposited at 4800 s owned a mixed texture of (111) and (200), showing an anisotropy distribution of (111)-oriented and (200)-oriented grains, while film deposited at 7200 s owned a strong (200) texture, displaying an isotropy distribution of (200)-oriented grains. The competitive growth between (111)-oriented and (200)-oriented grains was responsibility for alternating texture.

Template Synthesis of Indium Nanowires Using Anodic Aluminum Oxide Membranes

2008 ◽  
Vol 8 (9) ◽  
pp. 4488-4493 ◽  
Author(s):  
Feng Chen ◽  
Adrian H. Kitai
Keyword(s):  
Aluminum Oxide ◽  
Template Synthesis ◽  
Anodic Aluminum Oxide ◽  
Preferred Orientation ◽  
Hydraulic Pressure ◽  
X Ray Diffraction ◽  
Aao Template ◽  
X Ray ◽  
Anodic Aluminum ◽  
Oxide Membranes

Indium nanowires with diameters approximately 300 nm have been synthesized by a hydraulic pressure technique using anodic aluminum oxide (AAO) templates. The indium melt is injected into the AAO template and solidified to form nanostructures. The nanowires are dense, continuous and uniformly run through the entire ∼60 μm thickness of the AAO template. X-ray diffraction (XRD) reveals that the nanowires are polycrystalline with a preferred orientation. SEM is performed to characterize the morphology of the nanowires.

scholarly journals Solvent Concentration Effect on Powder X-Ray Diffraction and Dissolution Profiles of Acyclovir-Nicotinamide Cocrystals

2017 ◽  
Vol 7 (04) ◽  
Author(s):  
Setyawan D. ◽  
Siswandono Siswandono ◽  
Winantari A. N. ◽  
Zu’aimah K.
Keyword(s):  
Physical Properties ◽  
Oral Bioavailability ◽  
Ethanol Concentration ◽  
Antiviral Agent ◽  
X Ray Diffraction ◽  
Solvent Concentration ◽  
Solubility In Water ◽  
X Ray ◽  
Dissolution Properties ◽  
Slurry Method

Objective : Acyclovir (ACV) is well-known antiviral agent that has absorption problem, mainly due to its poor solubility in water and oral bioavailability. To improve acyclovir physical properties, especially dissolution properties, acyclovirnicotinamide(NCT) cocrystal was formed. Methods : ACV-NCT cocrystal was prepared using slurry method using ethanol as solvent with different concentration. The ACV-NCT cocrystal from each sample groups was characterized using powder X-ray diffraction (PXRD), and then dissolution properties evaluated. Results : Each ACV-NCT cocrystals prepared from slurry method with different ethanol concentrations have different PXRD profile. Dissolution analysis (ED15) showed that ACV-NCT cocrystallization using slurry methods with 10,0 ml/g as ethanol concentration significantly increase ED15 values compared to acyclovir and acyclovir-nicotinamide physical mixture (α=0,05). Conclusion : ACV-NCT cocrystal successfully formed using slurry method with 10,0 ml/g as optimal ethanol concentration.

Synthesis and Characterization of Cu2FeSnS4 Semiconductor Nanocrystals with Zincblende Structure

2012 ◽  
Vol 512-515 ◽  
pp. 2019-2022 ◽  
Author(s):  
Xiao Lu Liang ◽  
Xian Hua Wei
Keyword(s):  
Random Distribution ◽  
Semiconductor Nanocrystals ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Nir Absorption ◽  
Average Size

Cu2FeSnS4semiconductor nanocrystals with zincblende structure have been successfully synthesized by a hot-injection approach. Cu+, Fe2+, and Sn4+cations have a random distribution in the zincblende unit cell, and the occupancy possibilities are 1/2, 1/4 and 1/4, respectively. Those nanocrystals were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive spectroscopy (EDS), and UV-Vis-NIR absorption spectroscopy. The Cu2FeSnS4 nanocrystals have an average size of 7.5 nm and a band gap of 0.92 eV.

Direct X-Ray Measurement of Residual Strains in Textured Steel

1983 ◽  
Vol 27 ◽  
pp. 197-206
Author(s):  
C. P. Gazzara
Keyword(s):  
Residual Stress ◽  
Crystal Lattice ◽  
Elastic Constants ◽  
Random Distribution ◽  
Elastic Anisotropy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Residual Strains ◽  
Residual Stress Analysis ◽  
Textured Materials

One of the most detrimental effects on the accuracy of an X-ray diffraction residual stress analysis, XRDRSA(l), is found in the examination of textured materials. The degree of elastic anisotropy and texture is in general agreement with the extent of the error in the residual stress. Several approaches have been made to correct for the effects of texture, particularly involving experimental techniques. Reviews of such efforts are given by H. D811e(2), v.M. Hauk﹛3) and G. Maeder, J.L. Lebrun and J.M. Sprauel (4), just to mention a few.A brief chronology of the texture corrections involved in XRDRSA follows. With isotropic materials the d spacing of a crystal lattice, d, is assumed to vary linearly with sin2ψ. With textured materials the d vs sin2ψ relationship is nonlinear. This is due to the anisotropy of the elastic constants and their departure from a random distribution, or taking on a preferred orientation.

scholarly journals Mechanochemical Formation of Racemic Praziquantel Hemihydrate with Improved Biopharmaceutical Properties

Pharmaceutics ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 289
Author(s):  
Debora Zanolla ◽  
Dritan Hasa ◽  
Mihails Arhangelskis ◽  
Gabriela Schneider-Rauber ◽  
Michele R. Chierotti ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Polymorphic Form ◽  
In Vitro Tests ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Experimental Conditions ◽  
Intrinsic Dissolution ◽  
Intrinsic Dissolution Rate ◽  
X Ray ◽  
Enhanced Solubility

Praziquantel (PZQ) is the first-line drug used against schistosomiasis, one of the most common parasitic diseases in the world. A series of crystalline structures including two new polymorphs of the pure drug and a series of cocrystals of PZQ have been discovered and deposited in the Cambridge Structural Database (CSD). This work adds to the list of multicomponent forms of PZQ a relevant example of a racemic hemihydrate (PZQ-HH), obtainable from commercial PZQ (polymorphic Form A) through mechanochemistry. Noteworthy, the formation of the new hemihydrate strongly depends on the initial polymorphic form of PZQ and on the experimental conditions used. The new PZQ-HH has been fully characterized by means of HPLC, Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Hot-Stage Microscopy (SEM), Powder X-Ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), FT-IR, polarimetry, solid-state NMR (SS-NMR), solubility and intrinsic dissolution rate (IDR), and in vitro tests on Schistosoma mansoni adults. The crystal structure was solved from the powder X-ray diffraction pattern and validated by periodic-DFT calculations. The new bioactive hemihydrate was physically stable for three months and showed peculiar biopharmaceutical features including enhanced solubility and a double intrinsic dissolution rate in water in comparison to the commercially available PZQ Form A.

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