Lipid microspheres, preparation

In this study we incorporated PGEj and a PGI2 derivative into lipid microspheres, and the tissue distribution and clinical effectiveness of these lipo-preparations were studied. 

Preparation of lipid microspheres. The lipid microspheres (lipo-PGEj) with a diameter of 0.2 to 0.3 p m arc prepared from the drug, soybean oil and lecithin (Figure 1). The drug to be enclosed in the microspheres is first dissolved in soybean oil, and then emulsified with lecithin by a Manton-Gaulin homogenizer (7,2). 

Tissue distribution of lipo-preparations. The tissue distribution of lipid microspheres in normal and pathologic animals was studied. Research into liposomes of similar size suggested that lipid microspheres accumulated preferentially in the reticuloendothelial system, inflammatory sites, or certain tumors. The distribution of lipid microspheres to these tissues has been found in our studies (7,2). Interestingly, our study showed that lipid microspheres accumulated, particularly at high concentrations, in damaged vascular walls such as atherosclerotic vascular walls. 

Emulsions and suspensions are colloidal dispersions of two or more immiscible phases in which one phase (disperse or internal phase) is dispersed as droplets or particles into another phase (continuous or dispersant phase). Therefore, various types of colloidal systems can be obtained. For example, oil/water and water /oil single emulsions can be prepared, as well as so-called multiple emulsions, which involve the preliminary emulsification of two phases (e.g., w/o or o/w), followed by secondary emulsification into a third phase leading to a three-phase mixture, such as w/o/w or o/w/o. Suspensions where a solid phase is dispersed into a liquid phase can also be obtained. In this case, solid particles can be (i) microspheres, for example, spherical particles composed of various natural and synthetic materials with diameters in the micrometer range solid lipid microspheres, albumin microspheres, polymer microspheres and (ii) capsules, for example, small, coated particles loaded with a solid, a liquid, a solid-liquid dispersion or solid-gas dispersion. Aerosols, where the internal phase is constituted by a solid or a liquid phase dispersed in air as a continuous phase, represent another type of colloidal system. 

QF14 Preparation of lipid microspheres Imaging agent Injectable 355-42-0 May 2002/ Imcor PH... 

Albertini B, Passerini N, Di Sabatino M, Vitali B, Brigidi P, Rodriguez L (2009) Polymer-lipid based muco-adhesive microspheres prepared by spray-congealing for the vaginal delivery of econazole nitrate. European Journal of Pharmaceutical Sciences 36 591-601. 

Mu L and Feng S.S.(2001). Fabrication, characterization and in vitro release of paclitaxel (Taxol ) loaded poly (lactic-co-glycolic acid) microspheres prepared by spray drying technique with lipid/cholesterol emulsifiers. Journal of Controlled Release,Volume 76, Issue 3, pp 239-254. 

S. Sugiura, M. Nakajima, J.H. Tong, H. Nabetani, M. Seki, Preparation of monodispersed solid lipid microspheres using a microchannel emulsification technique./oumoJ of Colloid and Interface Science, 2000, 227, 95-103. 

Sugiura S, Nakajima M, Tong J, Nabetani H, Seki M. 2000. Preparation of monodis-persed solid lipid microspheres using a microchannel emulsification technique. J Colloid Interface Sci 227 95-103. 

Liposomes are formed due to the amphiphilic character of lipids which assemble into bilayers by the force of hydrophobic interaction. Similar assemblies of lipids form microspheres when neutral lipids, such as triglycerides, are dispersed with phospholipids. Liposomes are conventionally classified into three groups by their morphology, i.e., multilamellar vesicle (MLV), small unilamellar vesicle (SUV), and large unilamellar vesicle (LUV). This classification of liposomes is useful when liposomes are used as models for biomembranes. However, when liposomes are used as capsules for drugs, size and homogeneity of the liposomes are more important than the number of lamellars in a liposome. Therefore, "sized" liposomes are preferred. These are prepared by extrusion through a polycarbonate... 

The procedure for the preparation of cross-linked chitosan microspheres coated with polysaccharide or lipid for intelligent drug delivery systems is illustrated in Fig. 11 [230]. 

We prepared lipid-protein and lipid-polymer artificial cells to encapsulate biologically active materials. Later, Gregoriadis prepared concentric lipid manbrane liposomes containing enzymes. " Liposomes feature multiple lipid layers and onion-skin-like microspheres originally used by Bangham for basic membrane research. Workers in liposomes turned to preparing small submicron artificial... 

J. Tong, M. Nakajima, H. Nabetani, Preparation of phospholipid oil-in-water microspheres by microchannel emulsification technique, Eur. J. Lipid Sci. Technol. 2002, 104, 216-221. 

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