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Prevention of Microbial Contamination during Manufacturing
Published in Philip A. Geis, Cosmetic Microbiology, 2020
Deep-bed filtration or multimedia/sand filters are used to remove suspended material such as particulate matter, colloidal matter, and heavy molecular weight matter such as naturally occurring organic matter. The installation of an activated carbon bed is used to absorb chlorine, chloramines and organic material from a potable or drinking water source. Water softeners are used to remove calcium, magnesium and other cations that can cause water hardness. A reverse osmosis unit is a purification technology in which a semi-permeable membrane is used to remove both multivalent and monovalent ions from water. Depending upon the water quality, reverse osmosis units be either a single or a double pass. In a double-pass reverse osmosis unit, two individual reverse osmosis units are operated in a series in which one unit will provide the feedwater to the second unit. Cation/anion/mixed bed ion exchange columns or electrodeionization unit (EDI) unit is used to remove cations and anions from water that had not been removed by the reverse osmosis unit.
Body fluids and electrolytes
Published in Peate Ian, Dutton Helen, Acute Nursing Care, 2020
Osmosis is the passive movement of water across a selectively permeable membrane, from an area of lower solute concentration to an area of higher solute concentration. The membrane is fully permeable to water but selectively permeable to solutes. Osmosis ceases when there has been enough fluid movement to equalise the solute concentration on either side of the membrane. In clinical practice, you may hear the expression ‘water follows salt’ (see Figure 4.3). In practice, this means that water can flow easily across cell membranes if the solutions on either side cease to be isotonic, as occurs in dehydration.
Neuropathology
Published in Burkhard Madea, Asphyxiation, Suffocation,and Neck Pressure Deaths, 2020
Wolfgang Keil, Claire Delbridge
Oedema develops as a result of the rapid drop in oxidative metabolism in the neurons, the glia, the endothelial cells of the blood vessels and the choroid plexus. The abrupt lack of energy leads to the breakdown of homeostatic conditions. In the acute hypoxic−ischaemic phase, the ion pump of the neuroglia and neurons, in particular the activity of the Na+/K+−ATPase, quickly comes to a standstill. As a result, the Na+ concentration increases intracellularly and the K+ concentration decreases. The resulting membrane depolarization leads to Cl− influx into the cells. Due to osmosis, water reaches the intracellular space and the cells swell. The glial cells in particular absorb water in order to compensate for the intracellular increase in osmolarity. Aquaporin-4 obviously plays a role as a mediator. This intracellular oedema, called cytotoxic oedema, occurs first. The subsequent collapse of the blood−brain barrier causes the formation of vasogenic oedema. As a result, proteins are transported extravasally and draw water into the interstitial space through osmosis. As a result, the volume of the interstitial space increases [2, 4, 5].
Multi-fractal modeling of curcumin release mechanism from polymeric nanomicelles
Published in Drug Delivery, 2022
Camelia E. Iurciuc (Tincu), Marcel Popa, Leonard I. Atanase, Ovidiu Popa, Lacramioara Ochiuz, Paraschiva Postolache, Vlad Ghizdovat, Stefan A. Irimiciuc, Maricel Agop, Constantin Volovat, Simona Volovat
The intense research of the last four decades has allowed the development of extremely diverse polymer-drug systems, classified according to several criteria. One of them takes into account the release mechanism and kinetics of the active principle contained. We can thus distinguish three important categories, each of them being divided into other subcategories: (i) diffusion-controlled systems; (ii) erosion-controlled systems; (iii) osmosis-controlled systems. To these three main types, polymer systems are added to which the release of the active ingredient is controlled by ion exchange, or polymer-drug conjugates to which the release of the active ingredient is determined by the kinetics of the hydrolysis of chemical bonds between it and the macromolecular support (Shaik et al., 2012; Vilos & Velasquez, 2012).
Development and optimization of osmotically controlled drug delivery system for poorly aqueous soluble diacerein to improve its bioavailability
Published in Drug Development and Industrial Pharmacy, 2020
Magdy I. Mohamed, Abdulaziz M. Al-Mahallawi, Sami M. Awadalla
Osmotic pump Controlled Release Preparation is a novel drug delivery system. It gains a vital interest in oral solid dosage form development chiefly because of their ability to deliver drugs at constant rates (zero-order release) independent of media pH and hydrodynamics of the surrounding media [14,15]. Osmosis can be defined as the spontaneous movement of a solvent from a lower solute solution to a solution of higher solute concentration through an ideal semi-permeable membrane, which is permeable only to the solvent but impermeable to the solute [16,17]. The preparation consists of the core that contained the active material, a semi-permeable membrane that coated the core and an orifice, produced by a micro drill or mechanically to release the active material. When the system is in the gastrointestinal tract, fluid enters into the preparation and dissolves the active material within the core [14,17]. Thus the pressure formed in the preparation induces a release of the solution at a slow but continuous rate [18,19]. Therefore, solubility is considered one of the most vital factors affecting the drug release kinetics from the osmotic pump. As well as Osmotic pressure is another vital factor that imbibes water inside the osmotic pump, and it is proportional to the concentration of the osmotic agent [14].
Sustained release formulation of Ondansetron HCl using osmotic drug delivery approach
Published in Drug Development and Industrial Pharmacy, 2020
Ramakant Gundu, Sanjay Pekamwar, Santosh Shelke, Santosh Shep, Deepak Kulkarni
Osmotic systems utilize the principle of osmotic pressure for the delivery of drugs [10]. Drug release from these systems is independent of pH and other physiological parameter to a large extent and it is possible to modulate the release characteristic by optimizing the properties of drug and system. Osmosis refers to the net movement of solvent molecules across a semipermeable membrane from higher to lower solute concentration [11]. Push–pull osmotic pump tablet characterized by swellable pull layer which pull the drug outside from osmotic pump after pushing by swellable push layer [12]. It is a bilayer tablet coated with a semi permeable membrane. The upper compartment contained the drug; lower compartment contained high viscosity polymers, osmogent and was connected to the outside environment via a small delivery orifice. Polyethylene oxide (around 50–70%) was most commonly used polymer in pull and push layer. The system also had the disadvantage of higher cost compare to other extended release products [13].