Current Issue : April - June Volume : 2014 Issue Number : 2 Articles : 5 Articles
In this study, a hybrid multi-scale model has been developed for a continuous\r\nfluid bed wet granulation process by dynamically coupling computational fluid dynamics\r\n(CFD) with a discrete element model (DEM) and population balance model (PBM). In this\r\nprocess, the granules are formed by spraying the liquid binder on the fluidized powder bed.\r\nThe fluid flow field has been solved implementing CFD principles and the behavior of the\r\nsolid particles has been modeled using DEM techniques whereas the change in particle size\r\nhas been quantified with the help of PBM. The liquid binder droplets have been modeled\r\nimplicitly in DEM. A detailed understanding of the process aids in the development of better\r\ndesign, optimization and control strategies. The model predicts the evolution of important\r\nprocess variables (i.e., average particle diameter, particle size distribution (PSD) and particle\r\nliquid content) over time, which have qualitative similarity with experimentally observed\r\ntrends. The advantage of incorporating the multi-scale approach is that the model can be\r\nused to study the distributions of collision frequencies, particle velocity and particle liquid\r\ncontent in different sections of the fluid bed granulator (FBG), in a more mechanistic manner....
The aim of this study was to develop a user-friendly model for spray drying that can aid in the development of a\r\npharmaceutical product, by shifting from a trial-and-error towards a quality-by-design approach. To achieve this, a spray\r\ndryer model was developed in commercial and open source spreadsheet software. The output of the model was first fitted\r\nto the experimental output of a Bu�¨ chi B-290 spray dryer and subsequently validated. The predicted outlet temperatures of\r\nthe spray dryer model matched the experimental values very well over the entire range of spray dryer settings that were\r\ntested. Finally, the model was applied to produce glassy sugars by spray drying, an often used excipient in formulations of\r\nbiopharmaceuticals. For the production of glassy sugars, the model was extended to predict the relative humidity at the\r\noutlet, which is not measured in the spray dryer by default. This extended model was then successfully used to predict\r\nwhether specific settings were suitable for producing glassy trehalose and inulin by spray drying. In conclusion, a spray\r\ndryer model was developed that is able to predict the output parameters of the spray drying process. The model can aid the\r\ndevelopment of spray dried pharmaceutical products by shifting from a trial-and-error towards a quality-by-design\r\napproach....
Electrostatic fiber formation, also known as ââ?¬Å?electrospinningââ?¬Â, has emerged in recent years as the popular choice for producing continuous threads, nano fiber arrays and nonwoven fabrics with fiber diameters below 1Ã?µm for a wide range of materials. The process is divided into five operational components: fluid charging, formation of the cone-jet, thinning of the steady jet, onset and growth of jet instabilities that give rise to diameter reduction into the submicron regime, and collection of the fibers. Dependence of the jetting phenomenon on operating variables is discussed. Electrospun polymeric fibers are attractive candidates in the development of scaffolds for the tissue engineering and for providing new systems for delivery of bioactive molecules. Electrospinning has gained widespread interest due to its potential to produce nanofibers having high porosity similar to the natural extracellular matrix (ECM). The inherently high surface to volume ratio of electrospun scaffolds can enhance cell attachment, drug loading, and mass transfer properties....
Nanosizing is a suitable method to enhance the dissolution rate and therefore the bioavailability of poorly soluble drugs. The\r\nsuccess of the particle size reduction processes depends on critical factors such as the employed technology, equipment, and drug\r\nphysicochemical properties. High pressure homogenization and wet bead milling are standard comminution techniques that have\r\nbeen already employed to successfully formulate poorly soluble drugs and bring them to market. However, these techniques have\r\nlimitations in their particle size reduction performance, such as long production times and the necessity of employing a micronized\r\ndrug as the starting material. This review article discusses the development of combinative methods, such as the NANOEDGE, H\r\n96, H 69, H 42, and CT technologies. These processes were developed to improve the particle size reduction effectiveness of the\r\nstandard techniques. These novel technologies can combine bottom-up and/or top-down techniques in a two-step process. The\r\ncombinative processes lead in general to improved particle size reduction effectiveness. Faster production of drug nanocrystals and\r\nsmaller final mean particle sizes are among the main advantages. The combinative particle size reduction technologies are very\r\nuseful formulation tools, and they will continue acquiring importance for the production of drug nanocrystals....
Many problems associated with the mixing process remain unsolved and result in poor mixing performance.The residence time\r\ndistribution (RTD) and the mixing time are the most important parameters that determine the homogenisation that is achieved\r\nin the mixing vessel and are discussed in detail in this paper. In addition, this paper reviews the current problems associated with\r\nconventional tracers, mathematical models, and computational fluid dynamics simulations involved in radiotracer experiments\r\nand hybrid of radiotracer....
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