Recent developments in advanced thermal analysis: sample controlled thermal analysis

The determination of the key physical and chemical properties of a new material is essential.The melting point, glass transition temperature, the number and identification of the different phases it may have, and the temperatures at which they are formed are all of great value, not only in assessing its practical pharmaceutical potential but also as they can form the basis of many routine QC procedures

Predicting human intestinal absorption in the presence of bile salt with micellar liquid chromatography

Understanding intestinal absorption for pharmaceutical compounds is vital to estimate bioavailability and therefore the in vivo potential of a drug. This study considers the application of micellar liquid chromatography (MLC) to predict passive intestinal absorption with a selection of model compounds. MLC is already known to aid prediction of absorption using simple surfactant systems however, with this study the focus was on the presence of a more complex, bile salt surfactant, as would be encountered in the in vivo environment. As a result, MLC using a specific bile salt has been confirmed as an ideal in vitro system to predict the intestinal permeability for a wide range of drugs, through the development of a quantitative partition-absorption relationship. MLC offers many benefits including environmental, economic, time-saving and ethical advantages compared with the traditional techniques employed to obtain passive intestinal absorption values

Prediction of human intestinal absorption using micellar liquid chromatography with an aminopropyl stationary phase

The extent of human intestinal absorption (HIA) for a drug is considered to be an important pharmacokinetic parameter which must be determined for orally administered drugs. Traditional experimental methods relied upon animal testing and are renowned for being time consuming, expensive as well as being ethically unfavourable. As a result, developing alternative methods to evaluate a drug's pharmacokinetics is crucial. Micellar liquid chromatography (MLC) is considered to be one of these methods that can replace the use of animals in prediction of HIA. In this study, the combination of an aminopropyl column with the biosurfactant sodium deoxycholate (NaDC) bile salt were used in the experimental determination of micelle-water partition coefficients (log Pmw) for a group of compounds. Multiple linear regression (MLR) was then used for the prediction of HIA using the experimentally determined log Pmw along with other molecular descriptors leading to the construction of a model equation of R2= 85 % and a prediction power represented by R2Pred. =72 %. The use of MLC with an aminopropyl column in combination with NaDC was found to be a good method for the prediction of human intestinal absorption, providing data for a far wider range of compounds compared with previous studies

Thermal analysis in oxidative and pyrolysis conditions of alkaline earth metals picolinates using the techniques:TG-DSC, DSC, MWTA, HSM and EGA (TG-DSC-FTIR and HSM-MS)

Made available in DSpace on 2019-10-06T15:58:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-10-01Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)University of HuddersfieldSynthesis, characterization, thermal stability and pyrolysis of some alkaline earth picolinates M(C6H5NO2)2⋅nH2O (where M = Mg(II), Ca(II), Sr(II) and Ba(II) and n = di (Mg), mono (Ca), hemi three (Sr) hydrated) were investigated using a range of techniques including simultaneous thermogravimetry and differential scanning calorimetry (TG–DSC), evolved gas analysis (EGA), differential scanning calorimetry (DSC), Hot-Stage microscopy (HSM), powder X-ray diffractometry (PXRD), complexometry with EDTA and elemental analysis (EA). The TG-DSC curves show that the hydrated compounds dehydrate in a single step of mass loss and the thermal stability of the anhydrous compound is little influenced from the atmosphere used. On the other hand, the mechanisms of thermal decomposition are profoundly influenced by the atmosphere used, as can also be observed in the EGA data. In addition, a comparison between two calorimetric techniques, Microwave Thermal Analysis (MWTA) and DSC, was made which showed similar profiles. Two evolved gas analysis (EGA) techniques: TG-DSC coupled to FTIR and HSM coupled to a quadrupole mass spectrometer (MS) were also used to provide additional information about the pyrolysis mechanism.Universidade Estadual Paulista (UNESP) Instituto de QuímicaThermal Methods Research Unit Department of Chemistry University of Huddersfield, HuddersfieldInstituto Federal de Educação Ciência e Tecnologia do Paraná (IFPR)Instituto Federal de Educação Ciência e Tecnologia de Rondônia (IFRO)Universidade Estadual Paulista (UNESP) Faculdade de Ciências Departamento de QuímicaUniversidade Estadual Paulista (UNESP) Instituto de QuímicaUniversidade Estadual Paulista (UNESP) Faculdade de Ciências Departamento de Químic

Formation of a bile salt-drug hydrogel to predict human intestinal absorption

The unique character of bile salts to self-assemble into hydrogels in the presence of halide salts was exploited in this work to facilitate the prediction of human intestinal absorption (%HIA) for a set of 25 compounds. This was achieved by firstly incorporating each compound separately within the process of gel formation to create a series of gel-drug membranes. Scanning Electron Microscopy (SEM) analysis of the freeze-dried samples of the blank bile salt hydrogels and drug loaded bile salt hydrogels indicated a unique microstructure made of a network of intertwined fibrils. Drug-loaded sodium deoxycholate (NaDC) hydrogels were then utilised as the donor phase to study permeability using flow-through and static diffusion cells. The resulting values of the release-permeability coefficient (Kp) were then analysed, along with other molecular descriptors, for the prediction of human intestinal absorption (%HIA) using multiple linear regression (MLR). Overall, when comparing predicted values (using the systems presented in this study) with known literature values, it can be seen that both methods (i.e. using static and flow through cells) had good predictability with R2PRED. values of 79.8 % and 79.7 % respectively. This study therefore proposes a novel, accurate and precise way to predict human intestinal absorption for compounds of pharmaceutical interest using a simple in vitro permeation system. It is important to develop alternatives to the current methods used in prediction of HIA which are expensive and time consuming or include the use of animals. Therefore, the proposed method in this study being economic and time saving provides superiority over these current methods and suggests the possibility of its use as an alternate to such methods for prediction of HIA

The use of bile salt micelles for the prediction of human intestinal absorption

Human intestinal absorption (HIA) will dictate biopharmaceutical performance through its influence on absorption, distribution, metabolism, and elimination and can vary significantly depending upon the nature of the compound under consideration. In this study, an in vitro assay method is proposed for the prediction of HIA through the measurement of drug solubility in an aqueous phase containing micellar bile salt, namely sodium deoxycholate. A series of twenty compounds, displaying a range of physicochemical properties and known HIA values, were analyzed using UV spectroscopy to determine a solubilization ratio for each compound. A micelle/water partition coefficient (Kxm/a) was calculated and then used to develop an equation through simple linear regression; logit HIA = −0.919 + 0.4618 logKxm/a (R2 = 0.85). From this equation, a value for % HIA was determined which compared well with literature. Furthermore, 4 additional drugs were then analyzed using the developed equation and found to match well with literature, confirming the suitability of the method. Using a simple, economic, and robust UV bile salt assay allows prediction of HIA and avoids many of the disadvantages of other techniques, such as animal-based methods

The Renormalization Group with Exact beta-Functions

The perturbative $\beta$-function is known exactly in a number of supersymmetric theories and in the 't Hooft renormalization scheme in the $\phi_4^4$ model. It is shown how this allows one to compute the effective action exactly for certain background field configurations and to relate bare and renormalized couplings. The relationship between the MS and SUSY subtraction schemes in $N = 1$ super Yang-Mills theory is discussed

A novel method for the analysis of slash cuts to clothing

Slash attacks form a major element of physical assaults involving a sharp implement such as a knife. If the slash attack is inflicted onto a surface covered with fabric, such as clothing, then that fabric may receive a slash cut. Investigation of the slash cut can provide further information as to the nature of the implement and the action of the attack. This study aims to identify a quantifiable correlation between the nature of the slash cut and the implement causing said slash cut. The study also aims to develop a method of categorising the damage as well as a way of measuring the sharpness of a knife without blunting the blade. The two new simple techniques were developed and applied to a range of household implements. A quantifiable correlation could be seen between the damage categorisation and the relative sharpness of the implement. The degree of this correlation varied depending on the fabric type

Synthesis of Vegetable-Based Activated Carbons with Mixed Micro- and Mesoporosity for Use in Cigarette Filters

Activated carbons with micropores for adsorption and filtration of the volatile constituents of mainstream cigarette smoke, together with mesopores for enhanced mass transport were prepared by a novel route. Treatment of coconut shell or other lignocellulosic precursors with aqueous NaOH, followed by thorough washing, charring and steam activation produced carbons with enhanced adsorption characteristics in smoking trials, compared with their microporous analogues. The mechanism of formation of these carbons is explained in terms of initial partial dissolution of the precursor in an aqueous alkali solution, followed by catalytic gasification of carbon in steam involving residual sodium