Liposomes agents

Some questions have also been raised about the activity of liposomal agents prepared using polyanions because highly stable liposomes loaded with... 

Trlcock C (1995) Imaging tools Liposomal agents for nuclear medicine, computed tomography, magnetic resonance, and ultrasound. In Phrfippot JR, Schuber F (eds) Liposomes as tools in basic research and industry. CRC Press, Boca Raton, pp 225-240... 

In water, a particle of lecithin exhibits myelin growth, ie, cylindrical sheets that are formed by bdayers and are separated by water which may break up into liposomes (vesicles with a single bilayer of Hpid enclosing an aqueous space). PhosphoHpids more generally form multilamellar vesicles (MLV) (5). These usually are converted to unilamellar vesicles (ULV) upon treatment, eg, sonication. Like other antipolar, surface-active agents, the phosphoHpids are... 

The development of monoalkyl phosphate as a low skin irritating anionic surfactant is accented in a review with 30 references on monoalkyl phosphate salts, including surface-active properties, cutaneous effects, and applications to paste and liquid-type skin cleansers, and also phosphorylation reactions from the viewpoint of industrial production [26]. Amine salts of acrylate ester polymers, which are physiologically acceptable and useful as surfactants, are prepared by transesterification of alkyl acrylate polymers with 4-morpholinethanol or the alkanolamines and fatty alcohols or alkoxylated alkylphenols, and neutralizing with carboxylic or phosphoric acid. The polymer salt was used as an emulsifying agent for oils and waxes [70]. Preparation of pharmaceutical liposomes with surfactants derived from phosphoric acid is described in [279]. Lipid bilayer vesicles comprise an anionic or zwitterionic surfactant which when dispersed in H20 at a temperature above the phase transition temperature is in a micellar phase and a second lipid which is a single-chain fatty acid, fatty acid ester, or fatty alcohol which is in an emulsion phase, and cholesterol or a derivative. 

Presently, several clinical trials with liposome-encapsulated agents are under way and more are planned (Zonneveld and Crommelin, 1988 Klausner, 1988). During the last 5 years, key issues related to the pharmaceutical manufacturing of liposomes such as stability, sterilization, upscaling, and reproducibility have been successfully addressed. Although it is generally believed that a proper selection of the bi-layer components can minimize the occurrence of toxic effects due to the use of natural body constituents, the issue of liposome-related toxicity is not a trivial one and should be carefully studied,... 

D. (1985b). 5-Fluoroorotate A new liposome-dependent cytotoxic agent, FEBS Lett., 187, 73-75. 

Hirano, K., and Hunt, C. A. (1985). Lymphatic transport of liposome-encapsulated agents Effects of liposome size following intraperitoneal administration, J. Pharm. Sci., 74, 915-921. 

Mayhew, E., and Rustum, Y. (1983). Effect of liposome entrapped chemotherapeutic agents on mouse primary and metastatic tumors, Biol. Cell. 81-85. 

B. E. (1979). RadionucUde-labelled liposomes—A new lymph node imaging agent, Int. J. Nucl. Med. Biol.. 6, 75-83. 

Sculier, J. P., Coune, A., Brassine, C., Laduron, C., Atassi, G., Ruysschaert, J. M., and Fruhling, H. (1986). Intravenous infusion of high doses of liposomes containing NSC 251635, a water-insoluble cytostatic agent. A pilot study with pharmacokinetic data, J. Clin. Oncol., 4, 789-797. 

Probucol, another di-r-butyl phenol, is an anti-atherosclerotic agent that can suppress the oxidation of low-density lipoprotein (LDL) in addition to lowering cholesterol levels. The antioxidant activity of probucol was measured, using EPR, with oxidation of methyl linoleate that was encapsulated in liposomal membranes or dissolved in hexane. Probucol suppressed ffee-radical-mediated oxidation. Its antioxidant activity was 17-fold less than that of tocopherol. This difference was less in liposomes than in hexane solution. Probucol suppressed the oxidation of LDL as efficiently as tocopherol. This work implies that physical factors as well as chemical reactivity are important in determining overall lipid peroxidation inhibition activity (Gotoh et al., 1992). 

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