Research progress in the application of glass transition phenomenon in pharmaceutics / 药学学报

In recent years, the phenomenon of glass transition has been gradually applied to the field of pharmaceutics. And it exhibits important influences on multiple operating units of pharmaceutical preparations, and the properties and storage of pharmaceutical intermediates and products. At present, it has been widely used in the process of preparations such as drying, granulation, coating, tableting, holt-melt extrusion, cryogenic comminution, and so on. Meanwhile, it showed guiding significance for the process of preparation intermediates and their products, such as solid dispersion, microcapsule, liposome, particle, tablet, and other preparation intermediates and their products. Therefore, this article conducts a detailed analysis and systematic summary of the application guidance of the phenomenon of glass transition in the preparation process, and its influence on the preparation intermediates and products, so as to provide theoretical guidance for preparation production and product storage.

Glass transition of Chinese medicine extract powder and its application / 中国中药杂志

Glass transition theory is an important theory in polymer science, which is used to characterize the physical properties. It refers to the transition of amorphous polymer from the glassy state to the rubber state due to heating or the transition from rubber state to glassy state due to cooling. In this paper, the glassy state and glass transition of food and the similar relationship between the composition of Chinese medicine extract powder and food ingredients were described; the determination method for glass transition temperature (Tg) of Chinese medicine extract powder was established and its main influencing factors were analyzed. Meanwhile, the problems in drying process, granulation process and Chinese medicine extract powder and solid preparation storage were analyzed and investigated based on Tg, and then the control strategy was put forward to provide guidance for the research and production of Chinese medicine solid preparation.

Drying mechanism of "like-glass transition" and quality control strategy on Chinese materia medica pills / 中草药

Study on drying quality of pill (false drying, surface crust, and cracks) is the difficulty in pharmaceutic research of Chinese materia medica (CMM). The influence mechanism and relationship of quality of CMM pill during drying and storage are still in the experimental stage, and there is no more appropriate theory to explain and research. This paper attempts to use glass transition theory to explore drying characteristics and physical state change process and mechanism of quality change and to control the quality change of strategy of CMM pill during drying and storage.

Molecular dynamics of amorphous pharmaceutical fenofibrate studied by broadband dielectric spectroscopy$ / 药物分析学报

Fenofibrate is mainly used to reduce cholesterol level in patients at risk of cardiovascular disease. Thermal transition study with the help of differential scanning calorimetry (DSC) shows that the aforesaid active pharmaceutical ingredient (API) is a good glass former. Based on our DSC study, the molecular dynamics of this API has been carried out by broadband dielectric spectroscopy (BDS) covering wide temperature and frequency ranges. Dielectric measurements of amorphous fenofibrate were per-formed after its vitrification by fast cooling from a few degrees above the melting point (Tm ? 354.11 K) to deep glassy state. The sample does not show any crystallization tendency during cooling and reaches the glassy state. The temperature dependence of the structural relaxation has been fitted by single Vogel–Fulcher–Tamman (VFT) equation. From VFT fit, glass transition temperature (Tg) was estimated as 250.56 K and fragility (m) was determined as 94.02. This drug is classified as a fragile glass former. Deviations of experimental data from Kohlrausch–Williams–Watts (KWW) fits on high-frequency flank of α-peak indicate the presence of an excess wing in fenofibrate. Based on Ngai's coupling model, we identified the excess wing as true Johari–Goldstein (JG) process. Below the glass transition temperature one can clearly see a secondary relaxation (γ) with an activation energy of 32.67 kJ/mol.

Effect of different DE values of malto-dextrin on properties for Schisandrae Chinensis Fructus spray-dried powder / 中国中药杂志

The purpose of this study was to compare the effect of different DE values of malto-dextrin on Schisandrae Chinensis Fructus spray-dried powder. The glass transition temperature (Tg) of the spray-dried powder, powder properties and microscopic morphology were determined, and then the moisture absorption isotherms and the glass transition temperature were used to predict its storage stability. The study showed that after adding malto-dextrin, the powder rate was increased; moisture content was decreased; Tg was increased; mobility got better; produced spherical microstructure; and Tg was increased with the decrease of DE value. The water activity-equilibrium moisture content (aw-EMC) relationship in GAB models showed, the moisture absorption of powder was increased with the rising of DE value; and the equilibrium moisture content-glass transition temperature (EMC-Tg) relationship in Gordon-Taylor models showed that, Tg was decreased with the increase of moisture content. As a result, the storage critical condition of the spray-dried powder was improved, and along with the decrease of DE value, the critical water activity and the critical water content were increased. Therefore, the smaller the DE value, the greater the stability of the spray-dried powder.

Relevance of physical properties in the stability of plant-based food products.

Plant tissues are composed of a watery solution of low molecular weight species, mainly sugars, salts and organic acids, and of high molecular weight hydrocolloids, contained in a water insoluble matrix of macromolecules, mostly carbohydrates. All these constituents interact with water, thus reducing its thermodynamic vapour pressure (aw), with small molecules interacting through polar binding, and large biopolymers through surface and capillary effects. Similarly, some constituents will greatly affect kinetic glass transition temperatures (Tg), while others will not. As regards stability, while microbial and chemical changes are mainly related to aw, structure-related changes such as collapse are dependent on the glass transition temperature, Tg. In simple systems such as juices, both thermodynamic and kinetic approaches, employed respectively for high and low moisture systems, have predictive ability, which can be unified in the concept of “critical aw”. However, in complex, multidomain, multiphase systems, such as vegetables and fruits, where insoluble polymeric phases are present, hydrocolloids such as soluble pectins will only slightly affect Tg and aw, but significantly increase the macro viscosity of the soluble fraction, thereby reducing the tendency to collapse. In such cases the use of Tg as a predictive tool must be considered with care. The interrelationships among these aspects are discussed in detail below.

Preparation and characterization of a new kind of firm/soft adjusted poly(D,L-lactic acid)-polyurethane / 中国组织工程研究

10.3969/j.issn.2095-4344.2013.25.017

Use of glass transition temperature for stabilization of board's cracks of Eucalyptus grandis

The Eucalyptus grandis logs temperatures were determined and correlated with the board's cracks during steaming. Thermocouples were inserted in the logs center, registering their temperatures during steaming at 90"C. The logs were sawed and the board's cracks measured. It was concluded that: (1) the logistic S-shaped curve explains the logs temperature variation; (2) the logs with diameter of 20 to <25, 25 to <30 and 30 to <35 cm presented, respectively, 84.2"C, 73.1"C and 45.8"C in the steaming; and (3) the cracks lengths significantly decreased in logs that reached the glass transition temperature.

As temperaturas em toras de Eucalyptus grandis, durante a vaporização, foram determinadas e correlacionadas com as rachaduras das tábuas. Nos centros das toras foram inseridos termopares e registradas suas temperaturas durante a vaporização à 90"C. As toras foram desdobradas e as rachaduras das tábuas mensuradas. Concluiu-se que: (1) o modelo estatístico sigmoidal logístico explica a variação da temperatura nas toras; (2) as toras com 20 a <25, 25 a <30 e 30 a <35 cm de diâmetro apresentaram, respectivamente, 84,2"C, 73,1"C e 45,8"C ao final da vaporização; e (3) as rachaduras foramsignificativamente menores nas toras que atingiram a temperatura de transição vítrea.

Herramientas para el diseño de las condiciones del proceso de secado por aspersión de extractos vegetales para uso farmacéutico / Design tools for vegetable extract spray drying processes for pharmaceutical use

INTRODUCCIÓN: para la obtención en forma de polvo de los extractos y jugos de origen vegetal se emplea el secado por aspersión, porque es un método que preserva los componentes naturales presentes en estos productos. La presencia de compuestos como los azúcares impiden que estos puedan ser secados por aspersión sin que se adhieran a las superficies internas del equipo, lo que trae como consecuencia el bajo rendimiento en la recuperación del producto. El uso de aditivos inertes como el almidón soluble, celulosa o maltodextrina, favorece la recuperación del producto, elevando la temperatura de transición vítrea. OBJETIVOS: aplicar herramientas para el diseño del proceso de secado por aspersión de extractos de plantas. MÉTODOS: se determinaron las temperaturas de transición vítrea de diferentes extractos por calorimetría de barrido diferencial. Se calcularon las temperaturas de apelmazamiento y los índices individuales de secado. RESULTADOS: se determinó, que el uso de aditivos en el proceso de secado por aspersión de extractos de plantas permite obtener extractos en polvo en aquellos casos que no es posible secarlos solos. La metodología empleada, puede ser aplicada a distintos extractos. CONCLUSIONES: se demostró la factibilidad de la metodología propuesta como herramienta para definir la concentración de coadyuvante del secado y las temperaturas de secado

INTRODUCTION: to obtain extracts and juices of vegetal origin as powders, it is necessary to use the spray drying because this method preserves the natural compounds present in these products. Compounds like sugars prevent them from being spray dried without sticking to the inner surfaces of the dryer, all of which results in poor product recovery. The use of inert additives as soluble starch, cellulose or maltodextrin, favors the product recovery by increasing the glass transition temperature. OBJECTIVES: to use design tools for plant extract spray drying process. METHODS: the glass transition temperature was estimated for different extracts by differential scanning calorimetry. Sticking temperature as well as individual drying indexes were calculated. RESULTS: it was demonstrated that the use of additives in plant extract spray drying processes allows obtaining powdered extracts when it is not possible to dry the extract alone. This methodology can be applied to various extracts. CONCLUSIONS: the feasibility of the submitted methodology as a tool for defining adjuvant concentration and drying temperatures was shown

Glass transition and degree of conversion of a light-cured orthodontic composite

OBJECTIVE: This study evaluated the glass transition temperature (Tg) and degree of conversion (DC) of a light-cured (Fill Magic) versus a chemically cured (Concise) orthodontic composite. MATERIAL AND METHODS: Anelastic relaxation spectroscopy was used for the first time to determine the Tg of a dental composite, while the DC was evaluated by infrared spectroscopy. The light-cured composite specimens were irradiated with a commercial LED light-curing unit using different exposure times (40, 90 and 120 s). RESULTS: Fill Magic presented lower Tg than Concise (35-84ºC versus 135ºC), but reached a higher DC. CONCLUSIONS: The results of this study suggest that Fill Magic has lower Tg than Concise due to its higher organic phase content, and that when this light-cured composite is used to bond orthodontic brackets, a minimum energy density of 7.8 J/cm² is necessary to reach adequate conversion level and obtain satisfactory adhesion.

Polimerización ee ácido (dl) láctico mediante plicondensación por fusión direccta. estudio cinético de la etapa de oligomerización / Polymerizatio off dl lactic aid by direct melt polycondensation. kinetics sttudy of oligomerizatio stage

La reacción de polimerización del ácido láctico por el mecanismo de policondensación por fusión directa es de gran importancia cuando se desean obtener polímeros de bajo peso molecular, principalmente para aplicaciones médicas, debido a la facilidad del proceso y el bajo costo. Un ejemplo de esto es la elaboración de dispositivos para la liberación controlada de medicamentos. En este trabajo se estudiaron las diferentes etapas que involucra la policondensación (oligomerización y polimerización) para obtener PAL. La etapa de oligomerización se estudió en un estrecho intervalo de temperatura, 100-150 °C, donde el modelo cinético que describe la reacción es una ley de potencias de orden tres con Ea y factor preexponencial de 22,7 kcal/mol °K y 3,28x10-7 L²/mol²h respectivamente. Para la etapa de polimerización se estudiaron la influencia de la temperatura, el porcentaje de catalizador (SnCl2 2H2O) y el tiempo de reacción tomando como variable de respuesta la temperatur a de transición vítrea.

The polymerization reaction of d,1-lactic acid through polycondensation by direct melting is very important when low molecular weight polymers are desired, mainly for biomedical uses due to the easiness and low cost of process. And example of this is the manufacture of controlled delivery devices for drugs. In this work the steps involved on the polycondensation (oligomerization and polymerization) to obtain PLA were studied. The oligomerization was studied in a narrow range of temperatures 100-150°C where the kinetics model that describes the reaction is a kinetic law of powers of third order, with Ea and preexponential factor at 298.15K being 22,7 kcal/molK and 3.28x10-7 L²/mol²h respectively. For the polymerization step was studied the influence of temperature, the catalyst ratio (SnCL2.2H2O) and the time of reaction at the glassy transition temperature.

Study on the stability of glucosamine sulfate prepared by spray drying / 中国海洋药物

Objective To study the stability of glucosamine sulfate prepared by spray drying. Methods The microcapsules of glucosamine sulfate were produced by spray drying,and the effects of different adjuvants on the indices of the microcapsules,such as the yield,fluidity,glass transition temperature and store stability were compared. Results and conclusion The yield,fluidity,glass transition temperature and stability of glucosamine sulfate could be greatly improved by adding 0.5%,1.0%,2.0%,3.0% and 5.0% cyclodextrin,gelatin and copvidone.