A review on recent innovation in osmotically controlled drug delivery system.

In recent years, oral controlled release (CR) system is most acceptable dosage form by the patients. Drugs having short biological half-life and poor water solubility are the suitable candidate for development of CR system. They include dosage forms for oral and transdermal administration as well as injectable and implantable systems. For most of drugs, oral route remains as the most acceptable route of administration. Certain molecules may have low oral bioavailability because of solubility or permeability limitations. Development of an extended release dosage form also requires reasonable absorption throughout the gastro-intestinal tract (GIT). Among the available techniques to improve the bioavailability of these drugs fabrication of osmotic drug delivery system is the most appropriate one. The release of drug(s) from osmotic systems follows zero order. It is mainly governed by various formulation factors such as solubility and osmotic pressure of the core component(s), size of the delivery orifice, and nature of the rate-controlling membrane. The present review highlights an overview of OCDDS. And new technologies, fabrication and recent clinical research in osmotic drug delivery. Further, the challenges of these technologies and its future perspective are also discussed at length.

The mechanism, critical technology and progress of osmotic drug delivery systems / 国际药学研究杂志

As the typical example of controlled release preparation, osmotic pump-controlled release preparation is a new technique of preparation characterized by zero order release kinetics. Osmotic pressure is the motivation for releasing drug. The release behavior of osmotically controlled release systems is independent of external pH and food, and the in vivo-in vitro correlation is good, so they have attracted wide attention at home and abroad. After years of development, with the constant innovation of the mechanism, the structure of the osmotic pump has been continuously improved, and many products have been marketed. In this article, the development history and the mechanism of osmotic pump-controlled release preparation are briefly reviewed. Based on solubility, osmotic pressure, the delivery orifice and the coating membrane, the critical factors affecting the release rate and the research progress on osmotic pump controled release preparation are mainly discussed.

THE THYMIC STROMAL CELLS OF THE MICE AS DEMONSTRATED BY SEMIPERMEABLE MEMBRANE TECHNIQUE FOR NON-SPECIFIC ESTERASE / 解剖学报

Fresh cryostat sections from the thymus of BALB/c adult mice were processed with semipermeable membrane technique for demonstration of non-specific esterase (NE). The various cell types and the pattern of their distribution may be showed, because this technique may preserve the total enzyme activity of cells. The NE activity of epithelial reticular cells (ERC), thymic nurse cells (TNC), and interdigitating cells (IDC) are lower, but macrophages (M?) show a high activity. Cortical ERCs appear as a sponge-like network. Medullary ERCs may be divided into two cell types, i. e. low and high activity cells. The distribution of the latter shows foci-like pattern. M? present in both the cortex and medulla, in the cortico-medullary border they are prominent and may form rosettes-like structure with thymocytes. The thymus was also studied with immunohistochemical method using the monoclonal antibody of rat-anti-mouse thymic stromal ceils (MTS-6). This observation enable studies on the type of thymic stromal cells formed thymic microenvironment under LM.