Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Particulate form
Patent
1994-07-08
1997-07-15
Kishore, Gollamudi S.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Particulate form
424499, 424501, 264 41, 264 43, 264 433, 264 46, A61K 950, A61K 966
Patent
active
056480954
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to microparticles and their preparation, and more particularly to drug carriers for intranasal and intravaginal administration and to diagnostic aids, particularly echogenic materials for echocardiography and other purposes.
Microparticles, in the form of microspheres and microcapsules are well described in the pharmaceutical literature (for example, see the book, "Microspheres and Drug Therapy, Pharmaceutical Immunological and Medical Aspects", edited by S. S. Davis, L. Illum, J. G McVie and E. Tomlinson, Elsevier, Amsterdam, 1984). Such systems can be used as carriers for drugs and vaccines as diagnostic agents, and in surgical procedures (embolisation). Other applications can be identified in the field of cosmetics. The sizes of these microparticles can range from hundreds of microns to a few nanometres depending upon the application. Microparticulate drug delivery systems can be administered by a wide variety of routes but in particular, into the blood stream, into the muscle or subcutaneous space, into compartment of the body such as the pleura, into joints, into the eye, the respiratory system (nose and lungs), the gastrointestinal tract (to include buccal and rectal administration) and into the genitourinary tract (bladder instillation, vaginal administration).
It is known from EP-A-324-938 that air filled albumin microcapsules of about 1-10 .mu.m can be injected into the blood stream and will reflect ultrasonic radiation in such a way as to yield diagnostically useful images. These microbubbles are formed by first preparing microbubbles through a process of sonicating viscous albumin solutions. The resulting microbubbles are heat denatured to render the albumin water insoluble.
Starch is a natural microparticulate with a size in the 5 to 20 micron range. For more than a century, this material has been used as a pharmaceutical excipient. It has low immunogenicity and is biodegradable. Starch can be modified physically and chemically. This modification can conserve or destroy the granular nature of starch or can cause modifications at the molecular level. The properties of starch and derivatives thereof have been described in detail by Wurzburg, M. S. "Modified Starches, Properties and Uses", CRC Press, Boca Raton, 1986 and Gaillard, T. (Editor) "Starch: Properties and Potential", Critical reports on Applied Chemistry vol. 13, John Wiley, Chichester, 1987.
Mosbach, K. and Schroeder, U. in Enzyme Eng. 5 239-41 (1980) describe the preparation of magnetic microspheres where acid hydrolysed starch suspended together with magnetic material is poured into toluene containing a surfactant to give beads having a mean diameter of about 10 micron. The preparation of crystallized carbohydrate spheres has been described by Schroeder, U., St.ang.hl, A. and Salford, L. G. in Microspheres and Drug Therapy, Pharmaceutical, Immunological and Medical Aspects, Davis, S. S. et al Editors, Elsevier, Amsterdam, 1984, p. 427 and Schroeder, U. PCT/SE83/00268, 1983 (WO84/00294). Here, an aqueous carbohydrate solution is thoroughly mixed with substances to be entrapped and an emulsifying medium (corn, rape seed or cottonseed oil) added and an emulsion formed. This emulsion is then poured slowly into acetone containing a small concentration of non-ionic surface active agent. The carbohydrate spheres then precipitate and can be collected.
Ekman, B. M. and Lindahl, A. R. have used two immiscible aqueous phases to produce starch microspheres (EP-A-213303). The small spherical particles were produced by solidification of the dispersed droplets of a moderately soluble material (eg starch, agar, gelatin, pectin, collagen, carrageenin, fibrin), in a continuous phase of a second immiscible aqueous phase.
The formation of microcapsules by a double emulsion process from non-carbohydrate non-biodegradable materials has been proposed previously GB-A-1 288 583 for the preparation of organic pigment microcapsule for use in paints. The polymers used were insoluble polymers like polystyrene and there was no sugges
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Schroeder, U., Stahl,A. and Salford, L.G. in Microspheres and Drug Therapy, Pharmaceutical, Immunological and Medical Aspects, Davis et.al. Editors, Elsevier, Amsterdam, pp. 427-435 (1984).
Mosbach, K and Schroeder, U. in Enzeyme Eng. 5 239-41 (1980).
Illum Lisbeth
Johnson Olufunmiloyo Lilly
Danbiosyst UK Limited
Kishore Gollamudi S.
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