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Fluid Bed Processing
Published in Dilip M. Parikh, Handbook of Pharmaceutical Granulation Technology, 2021
Fluidization is the unit operation by which fine solids are transformed into a fluid-like state through contact with a gas. At certain gas velocities, the gas will support the particles, giving them freedom of mobility without entrainment. Such a fluidized bed resembles a vigorously boiling fluid, with solid particles undergoing extremely turbulent motion, which increases with gas velocity. The smooth fluidization of gas-solid particles is the result of an equilibrium between the hydrodynamic, gravitational, and interparticle forces.
Complex Pressure Relief Methods
Published in J G Webster, Prevention of Pressure Sores, 2019
The air fluidized bed was first described by Hargest and Artz in 1969 for treatment of burns. Air fluidization is an easy way to achieve many of the desirable requirements of patient support with a mechanically simple system. Air is compressed by a blower and then forced through a diffuser and into a mass of granular material (figure 7.5). This mass consists of silicosises, soda lime glass spheres in a range of 75–100 μm. When the air passes up through the mass, the spheres separate from one another and are suspended in the airflow issuing from the blower. By such means, a “fluid” is generated. The fluidized mass has a density 1.45 times that of water; thus the patient floats upon the bed rather than in it. When in the static state, the material appears to be a Fine white sand, but when fluidized it looks much like boiling milk (Hargest 1976).
Role of Tumor Cell Membrane in Hyperthermia
Published in Leopold J. Anghileri, Jacques Robert, Hyperthermia In Cancer Treatment, 2019
To avoid the lack of agreement with the physicochemical concept of fluidity, a new hyperthermia concept of “fluidization” has been proposed.139 This fluidization implies several changes which lead to reorganization of membrane properties: modification of membrane permeability and change of stereodistribution of macromolecules at the membrane surface. In this context, changes of bilayer fluidity may play just a part of the main role.153,154 This new, defined increase of fluidity or fluidization correlates with cell injury and death.155,156
Development of taste-masking microcapsules containing azithromycin by fluid bed coating for powder for suspension and in vivo evaluation
Published in Journal of Microencapsulation, 2023
Pham-Thi-Phuong Dung, Thanh-Dat Trinh, Quoc-Hoai Nguyen, Huu-Manh Nguyen, Ngoc-Chien Nguyen, Ngoc-Bao Tran, Cao-Son Tran, Thi-Hong-Ngoc Nguyen, Nguyen-Thach Tung
There are three types of fluid bed systems based on the site of nozzle: top-spray, bottom-spray, and tangential-spray (Saurabh and Garima 2010). In such fluid bed systems, the basic concept of fluidisation relies on the compensation of the gravity force experienced by the particles and an upward moving air flow, which ensures complete fluidisation of the particles. Typical fluidised bed apparatus can efficiently process particles from 100 mm to a few millimetres (Saurabh and Garima 2010). However, for very small particles, other forces such as electrostatic forces start to play a major role in the movement of the particles in the fluidisation chamber and prevent adequate fluidisation (Gouin 2004). Therefore, it is necessary to control the size of core particles loaded in coating chamber and key process parameters such as air flow, inlet temperature, spraying pressure, and spraying rate. In the first stage of this study, cores of bitter taste microcapsules were prepared by binding drug particles to get size of upper 125 µm. In the second stage, taste-masking layers were covered onto the core’s surface by fluid bed coating method.
Nanoemulsion-based dosage forms for the transdermal drug delivery applications: A review of recent advances
Published in Expert Opinion on Drug Delivery, 2022
Ankita Roy, Kumar Nishchaya, Vineet Kumar Rai
Most reports cite o/w type NE, facilitated with hydrogel, for transdermal application. Excess water ensures sufficient hydration and fluidization of SC, resulting in the swelling of the cells and creating wider networks for the movement of drugs. Moreover, hydration of structural proteins of the corneocytes disrupts the order of lipid bilayer membrane as it is covalently bound to lipidic chains of SC [42]. Additionally, the surfactants increase the permeation of the lipophilic drugs by altering the SC barrier and extracting the skin’s lipids. Viscosity is also essential to ensure better dosage form skin contact with minimum lag time. Thickening of a liquid NE provides better spread-ability and skin exposure. Partitioning helps in the distribution of the released drug to the lipidic environment of the skin [42].
Preparing of aspirin sustained-release granules by hot-melt granulation and micro-crystal coating
Published in Drug Development and Industrial Pharmacy, 2019
Ran Li, Tian Yin, Yu Zhang, Jingxin Gou, Haibing He, Xing Tang
After coating with isolation layer, ASP was coated with sustained layer with either Eudragit RS/RL30D or EC. When coated with Eudragit RS/RL30D, Eudragit RS/RL30D (RS:RL = 4:1, 7:3, and 3:2) and TEC (13.3%, 16.7%, and 20% of Eudragit RS/RL30D) were added to water, and stirred 30 min to prepare coating liquid with different weight gain (9%, 11%, and 14%), and the content of Eudragit RS/RL30D in water was 15%. ASP with isolation layer was placed in the fluidized bed for coating. The atomization pressure was controlled to be 2 bar, and the inlet air temperature was 28–32 °C. The spray speed was 1.5 g/min at the initial stage of coating, and was adjusted to 2.0 g/min after the coating process was stable. After the coating liquid was completely sprayed, the fluidization was continued for 20 min at a fluidization pressure of 25 m³/h to dry the material. The m-cG coated with Eudragit RS/RL30D was aged at 40 °C for 24 h after the coating process.