scholarly journals Control of the crystal form by the spherical crystallization technique. Factors causing polymorphism of tolbutamide spherical agglomerates.

1991 ◽  
Vol 28 (3) ◽  
pp. 172-176
Author(s):  
Akimitsu SANO ◽  
Takeo KURIKI ◽  
Yoshiaki KAWASHIMA ◽  
Hirofumi TAKEUCHI ◽  
Tomoaki HINO ◽  
...  
Keyword(s):  
Crystal Form ◽  
Spherical Crystallization ◽  
Spherical Agglomerates

IMPROVEMENT OF DISSOLUTION RATE OF FEBUXOSTAT USING HYBRID TECHNIQUE OF SPHERICAL CRYSTALLIZATION AND SOLID DISPERSION

INDIAN DRUGS ◽  
2015 ◽  
Vol 52 (09) ◽  
pp. 32-39
Author(s):  
D. B Tandel ◽  
◽  
P. A Shah ◽  
K. G. Patel ◽  
M. C Gohel ◽  
...  
Keyword(s):  
Solid Dispersion ◽  
Drug Dissolution ◽  
In Vitro Dissolution ◽  
Compatibility Study ◽  
Hybrid Technique ◽  
Spherical Crystallization ◽  
Spherical Agglomerates ◽  
Pvp K30 ◽  
Excipient Compatibility

The present study was carried out with an aim to improve dissolution rate of febuxostat (FBX, BCSclass II) drug. Spherical agglomerates were prepared by hybrid technique of spherical crystallization and solid dispersion using different ratios of FBX and polymer (PVP K30, HPMC E3LV and chitosan). Drug excipient compatibility study was evaluated by Fourier transform infrared spectroscopy and X-ray diffractometry. Scanning electron microscopy was used for measurement of size of agglomerate. In vitro dissolution study of prepared spherical agglomerates was compared with untreated FBX and marketed formulation in phosphate buffer pH 6.8. The ratio of drug to polymer also affected the drug dissolution results. Drug excipient compatibility study showed no interaction between FBX and PVP K30 (1:5) polymer. The use of PVP K30 (1:5) resulted in partial amorphization and improved drug dissolution. Direct compression method can be adopted in manufacturing to simplify the validation efforts. The performance of the formulated product was superior to the marketed product in the in vitro dissolution test.

scholarly journals Preparation of spherical agglomerates from potash alum

RSC Advances ◽  
2016 ◽  
Vol 6 (7) ◽  
pp. 5466-5473 ◽  
Author(s):  
Andrea F. Kardos ◽  
Judit Tóth ◽  
László Trif ◽  
János Gyenis ◽  
Tivadar Feczkó
Keyword(s):  
Core Material ◽  
Salt Hydrate ◽  
Spherical Crystallization ◽  
Spherical Agglomerates

Spherical crystallization proved to be feasible for the preparation of spherical salt hydrate particles as core material for microencapsulation.

scholarly journals Simple and Efficient Spherical Crystallization of Clopidogrel Bisulfate Form-I via Anti-Solvent Crystallization Method

Crystals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 53 ◽  
Author(s):  
Ji-Hun An ◽  
Alice Nguvoko Kiyonga ◽  
Eun Hee Lee ◽  
Kiwon Jung
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Processing Parameters ◽  
Polymorphic Form ◽  
Form Processing ◽  
Solvent Crystallization ◽  
Clopidogrel Bisulfate ◽  
Spherical Crystallization ◽  
Spherical Agglomerates

Clopidogrel bisulfate (CLP) form-I crystals are irregular, rectangular-shaped crystals. Because of their poor compressibility, flowability and their strong surface tension, manufacturers apply spherical crystallization methods to produce CLP form-I spherical agglomerates with a uniform particle size distribution. Consequently, manufacturers primarily synthesize CLP form-I crystal salts utilizing very complex methods, which produces form-I spherical agglomerates by means of spherical crystallization. In this study, spherical crystals of CLP Form-I were directly prepared from CLP Form-II, the most stable polymorph at room temperature, by using ethanol as solvent and a mixture of isopropyl alcohol (IPA)/n-Hexane (Hex) as an anti-solvent. To provide systematic inputs for the development of spherical agglomerates of optimal morphology, size, particle size distribution (PSD), and polymorphic form, processing parameters such as anti-solvent type, a mixture of IPA/Hex, pure Hex, or pure acetone; stirring speeds of 500, 600, 700, or 800 rpm; and temperatures ranging from 25 to 40 °C were explored. The effects of these parameters on spherical crystallization and polymorphic form were studied in terms of supersaturation, a driving force for polymorphic transformation, and the crystallization solution. Notably, our method does not require a large volume of anti-solvent which is the main complication of conventional anti-solvent crystallization methods.

scholarly journals Particle design of tolbutamide by the spherical crystallization technique. II. Factors causing polymorphism of tolbutamide spherical agglomerates.

1989 ◽  
Vol 37 (8) ◽  
pp. 2183-2187 ◽  
Author(s):  
Akimitsu SANO ◽  
Takeo KURIKI ◽  
Yoshiaki KAWASHIMA ◽  
Hirofumi TAKEUCHI ◽  
Toshiyuki NIWA
Keyword(s):  
Spherical Crystallization ◽  
Spherical Agglomerates

The native structure of the eukaryotic ribosome

1983 ◽  
Vol 41 ◽  
pp. 432-433
Author(s):  
R.A. Milligan ◽  
P.N.T. Unwin
Keyword(s):  
Ribosomal Proteins ◽  
Crystal Form ◽  
Native Structure ◽  
X Ray Diffraction ◽  
Eukaryotic Ribosome ◽  
Vitro Analysis ◽  
In Vitro Analysis ◽  
Resolution Structure ◽  
Stable Unit

A detailed understanding of the mechanism of protein synthesis will ultimately depend on knowledge of the native structure of the ribosome. Towards this end we have investigated the low resolution structure of the eukaryotic ribosome embedded in frozen buffer, making use of a system in which the ribosomes crystallize naturally.The ribosomes in the cells of early chicken embryos form crystalline arrays when the embryos are cooled at 4°C. We have developed methods to isolate the stable unit of these arrays, the ribosome tetramer, and have determined conditions for the growth of two-dimensional crystals in vitro, Analysis of the proteins in the crystals by 2-D gel electrophoresis demonstrates the presence of all ribosomal proteins normally found in polysomes. There are in addition, four proteins which may facilitate crystallization. The crystals are built from two oppositely facing P4 layers and the predominant crystal form, accounting for >80% of the crystals, has the tetragonal space group P4212, X-ray diffraction of crystal pellets demonstrates that crystalline order extends to ~ 60Å.

A Possible Basis for Nondestructive Characterization of Ropes of Nylon 6

1997 ◽  
Vol 503 ◽  
Author(s):  
H. Jiang ◽  
M. K. Davis ◽  
R. K. Eby ◽  
P. Arsenovic
Keyword(s):  
Tensile Strength ◽  
Service Life ◽  
Fiber Diameter ◽  
Structural Parameters ◽  
Crystal Form ◽  
Nylon 6 ◽  
Remaining Service Life ◽  
Nondestructive Characterization ◽  
Fractional Content

ABSTRACTPhysical properties and structural parameters have been measured for ropes of nylon 6 as a function of the number of use operations. The fractional content of the α crystal form, sound velocity, birefringence, tensile strength and length all increase systematically and significantly with increasing the number of use operations. The fractional content of the γ crystal form and fiber diameter decrease with use. These trends indicate that the measurement of such properties and structural parameters, especially the length, provide a possible basis for establishing a reliable, rapid, and convenient nondestructive characterization method to predict the remaining service life of nylon 6 ropes.

An Overview of Optimization of Spherical Crystallisation Process

2013 ◽  
Vol 6 (4) ◽  
pp. 2203-2209
Author(s):  
N B Bhagat ◽  
A V Yadav ◽  
P R Mastud ◽  
R A Khutale
Keyword(s):  
Physical Phenomenon ◽  
Chemical Properties ◽  
Spherical Shape ◽  
Particle Engineering ◽  
Spherical Crystallization ◽  
Stirring Rate ◽  
Physico Chemical ◽  
Rate Selection ◽  
Pharmaceutical Agents ◽  
Spherical Crystals

In this article we describe the optimizing parameters in the process of spherical crystallisation. Particle engineering of active pharmaceutical agents is an innovative area of research in pharmaceutical industry because of several advantages. Spherical crystallization is one of the particle engineering technique in which drug directly gets crystallized and agglomerated into spherical shape. The spherical crystals can be obtained by different methods like solvent change, Quasi-emulsion droplet, ammonia diffusion and neutralisation. The optimization of process of spherical crystallization is important for obtaining the ideal spherical crystal agglomerates. It includes stirring rate, selection of solvent, pH, temperature etc. which affects on the physico-chemical properties of crystals. These optimizing parameters play its specific role in formation of spherical crystals. Stirring rate affects the shape as well as size of the final agglomerates and solvent selection helps in the formation of maximum amount of agglomerates in the system. The factors like pH and temperature should be maintained in case of drugs which show polymorphism. Apart from this, several others physical phenomenon or parameters like interfacial tension and rate of crystallisation are also important for thorough optimization of process.  

Functional characterization and structural modelling of peptidoglycan degrading β-N-acetyl-glucosaminidase from a dental isolate of Serratia marcescens

2020 ◽  
Vol 23 ◽  
Author(s):  
Aditi Rathee ◽  
Anil Panwar ◽  
Seema Kumari ◽  
Sanjay Chhibber ◽  
Ashok Kumar
Keyword(s):  
Functional Characterization ◽  
Major Change ◽  
Crystal Form ◽  
Bound State ◽  
Dynamics Simulation ◽  
Gram Positive ◽  
Structural Cell ◽  
Stability Structure ◽  
Arginine Residues ◽  
The Stability

Introduction:: Enzymatic degradation of peptidoglycan, a structural cell wall component of Gram-positive bacteria, has attracted considerable attention being a specific target for many known antibiotics. Methods:: Peptidoglycan hydrolases are involved in bacterial lysis through peptidoglycan degradation. β-N-acetylglucosaminidase, a peptidoglycan hydrolase, acts on O-glycosidic bonds formed by N-acetylglucosamine and N-acetyl muramic acid residues of peptidoglycan. Aim of present study was to study the action of β-N-acetylglucosaminidase, on methicillin- resistant Staphylococcus aureus (MRSA) and other Gram-negative bacteria. Results:: We investigated its dynamic behaviour using molecular dynamics simulation and observed that serine and alanine residues are involved in catalytic reaction in addition to aspartic acid, histidine, lysine and arginine residues. When simulated in its bound state, the RMSD values were found lesser than crystal form in the time stamp of 1000 picoseconds revealing its stability. Structure remained stably folded over 1000 picoseconds without undergoing any major change further confirming the stability of complex. Conclusion:: It can be concluded that enzymes belonging to this category can serve as a tool in eradicating Gram-positive pathogens and associated infections.

scholarly journals Effects of Sources and Forms of Vitamin K3 on Its Storage Stability in Vitamin Premixes or Vitamin Trace Mineral Premixes

Animals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1140
Author(s):  
Huakai Wang ◽  
Pan Yang ◽  
Longxian Li ◽  
Nan Zhang ◽  
Yongxi Ma ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Storage Time ◽  
Storage Stability ◽  
Choline Chloride ◽  
Crystal Form ◽  
Negative Effects ◽  
Trace Mineral ◽  
Vitamin K3 ◽  
Choline Group ◽  
Micro Sphere

Six types of vitamin K3 (VK3); two sources (menadione sodium bisulfite, MSB; menadione nicotinamide bisulfite, MNB), and three different forms (crystal, micro-capsule, and micro-sphere) were used to determine the retention of VK3 in vitamin premixes (Experiment 1) or vitamin trace mineral (VTM) premixes (Experiment 2) after 1, 2, 3, and 6 months of storage. The retention of VK3 in vitamin premixes was evaluated at 25 °C/60% relative humidity or 40 °C/75% relative humidity in an incubator in Experiment 1 and in VTM premixes (choline chloride: 0 vs. 16,000 mg/kg) stored at room temperature in Experiment 2. The VK3 retention in vitamin premix or VTM premix decreased significantly with the extension of storage time (p < 0.05). In Experiment 1, the VK3 retention was higher in the 25 °C/60% incubator (56%) than in the 40 °C/75% incubator (28%). The MNB retention (52%) was higher than MSB retention (32%). The retention of VK3 in micro-capsules (43%) or micro-spheres (48%) was higher than the crystal form (35%) after six months of storage. In Experiment 2, there was no difference between the retention of MSB (49%) or MNB (47%). The retention of VK3 of micro-capsule (51%) or micro-sphere (54%) was higher than that of crystal form (40%). The VK3 retention was higher in the choline-free group (51%) than in the choline group (47%) after six months of storage. Finally, the predicted equations of VK3 retention with storage time in vitamin premixes or VTM premixes were established. The R2 of the prediction equations was ≥0.9005, indicating that time is an important factor in predicting VK3 retention. In conclusion, the higher temperature-relative humidity, choline had negative effects on VK3 retention during premix storage. MNB retention was higher than MSB during storage of vitamin premix. The encapsulated forms of VK3, micro-capsules and micro-spheres, could improve VK3 storage stability in vitamin premix and VTM premix.

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