scholarly journals Molecular Mobility and Stability Studies of Amorphous Imatinib Mesylate

Pharmaceutics ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 304 ◽  
Author(s):  
Bożena Karolewicz ◽  
Agata Górniak ◽  
Dominik M. Marciniak ◽  
Igor Mucha
Keyword(s):  
Relaxation Time ◽  
Imatinib Mesylate ◽  
Enthalpy Relaxation ◽  
Attenuated Total Reflectance ◽  
Molecular Relaxation ◽  
Scanning Calorimetry ◽  
Solid Dosage ◽  
Experimental Enthalpy ◽  
Time Parameters ◽  
The Mean

The proposed study examined the characterization and stability of solid-state amorphous imatinib mesylate (IM) after 15 months under controlled relative humidity (60 ± 5%) and temperature (25 ± 2 °C) conditions. After 2 weeks, and 1, 3, 6, and 15 months, the samples were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray powder diffractometry (XRPD), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM). Additionally, the amorphous form of imatinib mesylate was obtained via supercooling of the melt in a DSC apparatus, and aged at various temperatures (3, 15, 25 and 30 °C) and time periods (1–16 h). Glass transition and enthalpy relaxation were used to calculate molecular-relaxation-time parameters. The Kohlrausch–Williams–Watts (KWW) equation was applied to fit the experimental enthalpy-relaxation data. The mean molecular-relaxation-time constant (τ) increased with decreasing ageing temperature. The results showed a high stability of amorphous imatinib mesylate adequate to enable its use in solid dosage form.

Dielectric Studies. Part XXXV. Relaxation Studies of Benzaldehyde and Fourpara-Substituted Aideliydes

1974 ◽  
Vol 52 (18) ◽  
pp. 3229-3234 ◽  
Author(s):  
P. F. Mountain ◽  
S. Walker
Keyword(s):  
Hydrogen Bonding ◽  
Relaxation Time ◽  
Intermolecular Hydrogen Bonding ◽  
Dielectric Studies ◽  
Molecular Relaxation ◽  
Relaxation Data ◽  
Dielectric Absorption ◽  
The Mean ◽  
Relaxation Studies ◽  
Xylene Solution

The dielectric absorption has been determined for benzaldehyde, p-fluoro-, p-chloro-, p-bromo-, and p-nitro-benzaldehyde in p-xylene solution at mainly five or six frequencies in the 6.70 to 70.1 GHz region. For all three p-halo-substituents the mean relaxation time values indicate that some mechanism faster than molecular relaxation occurs whereas none was apparent in benzaldehyde itself. A detailed study has been made of p-chlorobenzaldehyde in p-xylene solution at five temperatures, and the data have been analyzed into contributions from a molecular relaxation process and a shorter relaxation time τ2. In the p-xylene solutions of benzaldehyde the relaxation data indicate weak intermolecular hydrogen bonding between the solute and the solvent which is probably of the type [Formula: see text]

Comparison of phaco time parameters in eyes with and without glaucoma filtration surgery due to pseudoexfoliation glaucoma

2021 ◽  
pp. 112067212110177
Author(s):  
Ayse Gul Kocak Altintas ◽  
Cagri Ilhan
Keyword(s):  
Clinical Characteristics ◽  
Pseudoexfoliation Glaucoma ◽  
Filtration Surgery ◽  
Glaucoma Filtration Surgery ◽  
Mean Values ◽  
Time Parameters ◽  
The Mean ◽  
Group 2 ◽  
Surgical Manipulations ◽  
Phaco Time

Purpose: To compare the phaco time parameters including ultrasound time (UST), effective phaco time (EPT), and average phaco power (APP) in eyes with pseudoexfoliation glaucoma (PEG) and had or had not glaucoma filtration surgery. Methods: In this retrospective comparative study, Group 1 was constructed with 84 PEG patients who had not operated previously, and Group 2 was constructed with 49 PEG patients who had glaucoma filtration surgery. The mean values of UST, EPT, and APP were compared. The preoperative clinical characteristics and surgical manipulations were also compared. Results: The mean ages and male-to-female ratios of the groups were similar ( p > 0.05, for both). There was no difference in the preoperative clinical characteristics, including biometric values between the groups ( p > 0.05, for all). Some surgical manipulations, including pupillary stretching ( p = 0.004), pupillary membrane peeling ( p = 0.021), iris hook using ( p = 0.041), and capsular tension ring implantation ( p = 0.041), were significantly performed more commonly in Group 2. Although the mean UST and EPT values were similar ( p > 0.05, for both), the mean APP value was significantly lower in Group 2 ( p = 0.011). Conclusion: The lower APP parameter was observed in PEG patients having had glaucoma filtration surgery. Needing more surgical manipulation to overcome poor pupillary dilation and weak zonular instability can be a reason for this result.

Shortening of muscle relaxation time after creatine loading

1999 ◽  
Vol 86 (3) ◽  
pp. 840-844 ◽  
Author(s):  
M. van Leemputte ◽  
K. Vandenberghe ◽  
P. Hespel
Keyword(s):  
Relaxation Time ◽  
Muscle Relaxation ◽  
Muscle Contractions ◽  
Contraction Time ◽  
Healthy Male ◽  
Healthy Male Volunteers ◽  
Torque Generation ◽  
Isometric Torque ◽  
The Mean ◽  
Isometric Muscle

The effect of creatine (Cr) supplementation on muscle isometric torque generation and relaxation was investigated in healthy male volunteers. Maximal torque (Tmax), contraction time (CT) from 0.25 to 0.75 of Tmax, and relaxation time (RT) from 0.75 to 0.25 of Tmax were measured during 12 maximal isometric 3-s elbow flexions interspersed by 10-s rest intervals. Between the pretest and the posttest, subjects ingested Cr monohydrate (4 × 5 g/day; n = 8) or placebo ( n = 8) for 5 days. Pretest Tmax, CT, and RT were similar in Cr and placebo groups. Also in the posttest, Tmax and CT were similar between groups. However, posttest RT was decreased consistently by ∼20% ( P < 0.05) in the Cr group from the first to the last of the 12 contractions. In addition, the mean decrease in RT after Cr loading was positively correlated with pretest RT ( r = 0.82). It is concluded that Cr loading facilitates the rate of muscle relaxation during brief isometric muscle contractions without affecting torque production.

Insight into the Formation of Ultrafine Nanostructures in Bulk Amorphous Zr54.5 Ti7.5Al10Cu20Ni8

2001 ◽  
Vol 703 ◽  
Author(s):  
André Heinemann ◽  
Helmut Hermann ◽  
Albrecht Wiedenmann ◽  
Norbert Mattern ◽  
Uta Kühn ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Volume Fraction ◽  
High Volume ◽  
High Resolution Electron Microscopy ◽  
Scattering Data ◽  
Scanning Calorimetry ◽  
Enhanced Diffusion ◽  
Resolution Electron ◽  
The Mean ◽  
Interparticle Interference

ABSTRACTBulk amorphous Zr54.5 Ti7.5Al10Cu20Ni8 is investigated by means of smal-angle neutron scattering (SANS), differential-scanning calorimetry (DSC), high-resolution electron microscopy (HREM) and other methods. The formation of ultrafine nanostructures in the glassy phase is observed and explained by a new model. Structura fluctuations of randomly distributed partialy ordered domains grow during annealing just below the glass transition temperature by local re-ordering. During anneaing the DSC gives evidence for a increasing volume fraction of the localy ordered domains. At high volume fractions of impinging domains a percolation threshold on the interconnected domain boundaries occurs and enhanced diffusion becomes possible. At that stage SANS measurements lead to satistically significant scattering data. The SANS signals are anayzed in terms of a model taking into account spherica particles surrounded by diffusion zones and interparticle interference effects. The mean radius of the nanocrystaline particles is determined to 1 nm and the mean thickness of the depletion zone is 2 nm. The upper limit for the volume fraction after annealing at 653 K for 4hours is about 20 %. Electron microscopy confirms the size and shows that the particle are crystaline.

scholarly journals Statistical studies of duration of low-power solar flares

2018 ◽  
Vol 4 (2) ◽  
pp. 8-16
Author(s):  
Александр Боровик ◽  
Aleksandr Borovik ◽  
Антон Жданов ◽  
Anton Zhdanov
Keyword(s):  
Low Power ◽  
Solar Flares ◽  
Flare Region ◽  
Statistical Studies ◽  
Time Parameters ◽  
The Mean ◽  
Using Data

This paper is a sequel to papers dealing with time parameters of solar flares in the Hα line. Using data from the international flare patrol for 1972–2010, we have determined the mean duration of flares of different importance and classes of area. We have established that 94.6 % of flares last more than 60 min. The duration of 90 % of flares with min is 2.1–3.3 hrs. In rare cases, flares can last about 12 hrs. The duration of powerful solar flares does not exceed 8.3 hrs. We have found that the duration of solar flares depends on features of their development. Flares with one brilliant point in the flare region have the shortest duration; two-ribbon flares and flares exhibiting several intensity maxima have the longest duration. We have confirmed that the duration of flares increases with increasing classes of area and brightness.

scholarly journals Compatibility Studies of Valsartan with Different Pharmaceutical Excipients

2019 ◽  
Vol 70 (7) ◽  
pp. 2590-2600
Author(s):  
Ioana Cristina Tita ◽  
Lavinia Lupa ◽  
Bogdan Tita ◽  
Roxana Liana Stan ◽  
Laura Vicas
Keyword(s):  
Magnesium Stearate ◽  
Dosage Forms ◽  
Compatibility Studies ◽  
Scanning Calorimetry ◽  
Pharmaceutical Dosage Forms ◽  
Lactose Monohydrate ◽  
Pharmaceutical Excipients ◽  
Solid Dosage ◽  
Fourier Transformed Infrared Spectroscopy ◽  
Ft Ir

Compatibility studies between active drugs and excipients are substantial in the pharmaceutical technology. Thermal analysis has been extensively used to obtain information about drug-excipient interactions and to perform pre-formulation studies of pharmaceutical dosage forms. The objective of the present study was to evaluate the compatibility of the valsartan (VALS) with pharmaceutical excipients of common use including diluents, binders, disintegrants, lubricants and solubilising agents. Thermogravimetry (TG), derivative thermogravimetry (DTG), but especially differential scanning calorimetry (DSC) were used for a first screening to find small variations in peak temperature and/or their associated enthalpy for six drug/excipient mixtures (starch, cross caramelose sodique, microcrystalline cellulose 102, povidone K30, lactose monohydrate and magnesium stearate), which indicate some degree of interaction. Additional methods using Fourier transformed infrared spectroscopy (FT-IR) and X-ray powder diffraction (XRPD) confirmed the incompatibility of VALS with starch, povidone K30, lactose monohydrate and magnesium stearate. Those excipients should be avoided in the development of solid dosage forms.

scholarly journals SOLID DOSAGE FORM DEVELOPMENT OF GLIBENCLAMIDE WITH INCREASING THE SOLUBILITY AND DISSOLUTION RATE USING COCRYSTALLIZATION

2018 ◽  
Vol 10 (6) ◽  
pp. 181
Author(s):  
Arif Budiman ◽  
Sandra Megantara ◽  
Putri Raraswati ◽  
Tazyinul Qoriah
Keyword(s):  
Dissolution Rate ◽  
Dosage Form ◽  
Crystallization Process ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Solid Dosage Form ◽  
Solid Dosage ◽  
Infra Red ◽  
Form Development

Objective: The aim of this study was to develop a solid dosage form of glibenclamide with increasing the solubility properties of glibenclamide with cocrystallization method.Methods: Virtual screening was performed to investigate the interaction between glibenclamide and a co-former. Saccharin, the selected co-former, then co-crystallized with glibenclamide with equimolar ratios of 1:1 and 1:2 using the solvent evaporation method. Further characterization was performed using an infra-red (IR) spectrophotometer, differential scanning calorimetry (DSC), and powder x-ray diffraction (PXRD).Results: Co-crystals of 1:2 equimolar ratio were more highly soluble compared to pure glibenclamide (30-fold for 12 h and 24-fold for 24 h). The dissolution rate had also increased from 46.838% of pure glibenclamide to 77.655% of glibenclamide co-crystal in 60 min. There was no chemical reaction observed during the co-crystallization process based on the IR spectrum. However, there was a new peak in the X-Ray diffractogram and a reduction of melting point in the DSC curve, indicating the formation of co-crystals.Conclusion: The optimal co-crystal ratio of glibenclamide-saccharin was found to be 1:2, which was successful in improving the solubility of glibenclamide.

Effects of chemical composition and mean coordination number on glass transitions in Ge–Sb–Se glasses

2017 ◽  
Vol 31 (36) ◽  
pp. 1750342 ◽  
Author(s):  
Wen-Hou Wei
Keyword(s):  
Glass Transition ◽  
Chemical Composition ◽  
Coordination Number ◽  
Structural Phase ◽  
Stoichiometric Composition ◽  
Glass Transitions ◽  
Fragility Index ◽  
Scanning Calorimetry ◽  
Transition Formula ◽  
The Mean

Glass transitions in the Ge–Sb–Se glasses were investigated by means of differential scanning calorimetry (DSC) under non-isothermal conditions. The glass transition temperature [Formula: see text], activation energy of glass transition [Formula: see text], and fragility index as functions of the mean coordination number (MCN) and atomic percent of Ge were examined. The maximum value of [Formula: see text] in each group of the glasses occurred at the chemically stoichiometric composition, suggesting a glass transition threshold. The [Formula: see text] and fragility index were calculated from the heating rate dependence of [Formula: see text]. Both [Formula: see text] and fragility index show the minima at MCN = 2.4 which can be attributed to the structural phase transition of a covalently glassy network at MCN = 2.4. The analysis of the experimental results suggests that both the chemical composition and MCN have significant effects on the glass transitions in Ge–Sb–Se glasses.

pH Responsive Polymeric Nanoparticles for Oral Insulin Delivery

2017 ◽  
pp. 6-10
Author(s):  
Charu Tyagi
Keyword(s):  
Insulin Release ◽  
Polymeric Nanoparticles ◽  
Attenuated Total Reflectance ◽  
Ph Responsive ◽  
Eudragit L100 ◽  
Release Studies ◽  
Mean Size ◽  
The Mean ◽  
In Vitro Insulin Release

Gelatin-eudragit L100 nanoparticles of wet size range 170-563nm were prepared by two step dissolvation method and the effect of different concentrations of eudragit L100 and emulsifying agent - sodium lauryl sulphate (SLS) - on the particle size were studied. Synthesized nanoparticles were characterized by attenuated total reflectance-fourier transform infrared spectroscopy (ATRFTIR) and the mean size distribution. Insulin loading was done at a pH 7.4 and the in vitro insulin release studies of nanoparticles were carried out by simulating gastrointestinal tract condition which showed the minimal insulin release at pH 2.5 (20% in 90min) while appreciable release (40% in first 30min) at pH of 7.4. This pH responsive release pattern of the synthesized nanoparticles confers on the insulin protection from proteolytic degradation in acidic environment of stomach and upper intestinal part while enhancing bioavailability in the later part of intestine.

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