Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Liposomes
Patent
1991-06-05
1993-10-12
Page, Thurman K.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Liposomes
424420, 4284022, 436829, A61K 9127
Patent
active
052523365
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
Technical Field
The present invention relates to a liposome composition.
Background Art
In general, among drugs which are effective in vitro, many of them disappear before sufficient manifestation of their activities at target sites due to rapid metabolism thereof after administration in vivo. As means for making such drugs more effective at target sites, various drug delivery systems (DDS) have been studied. In particular, DDS wherein a drug is encapsulated in liposome is useful for lasting blood level of the drug and targeting the drug toward a specific site and, therefore, it is considered to be an effective preparation. However, such liposome does not always manifest its function as DDS sufficiently after administration, and its function largely depends on the manufacturing conditions of the liposome and a particular kind of lipid used as the liposome membrane component.
As the major problems of liposome, encapsulation efficiency of a drug, stability of a liposome membrane for maintaining the encapsulated drug for a long period of time, and dispersibility of liposome are pointed out. In general, liposome prepared by using a lipid such as phospholipid or the like as the liposome membrane component is poor in dispersibility, which causes aggregation in a short period of time and often adversely affects the drug encapsulation properties and stability of the liposome. Such liposome is often incorporated in reticulo-endothelial system (RES) at an earlier stage after administration, which results in failure to manifest its function as DDS.
Accordingly, for the development of DDS using liposome, it is of importance to improve dispersibility to produce stable liposome.
OBJECTS OF THE INVENTION
The development of liposome with good dispersibility, high encapsulation property and higher stability by modification of the composition of a liposome membrane is not yet sufficient.
In view of these circumstances, the present inventors have studied intensively to obtain liposome with good dispersibility, high encapsulation property and higher stability by modification of the composition of the liposome membrane aiming at addition of a membrane modification component to the composition of the membrane.
Thus, the main object of the present invention is to provide novel liposome with good dispersibility, high encapsulation property and higher stability.
This object as well as other objects and advantages of the present invention will be apparent to those skilled in the art from the following description with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows change of blood level of lipid after administration of the liposome compositions shown in Experiment 4 hereinafter, wherein , , , .quadrature. and represent the liposome compositions of Examples 2, 3, 4 and 5 as well as Sample 1 hereinafter, respectively.
FIG. 2 shows change of blood level of lipid after administration of the liposome compositions shown in Experiment 4 hereinafter, wherein , , and represent the liposome compositions of Examples 6, 7 and 8 as well as Sample 1 hereinafter, respectively.
SUMMARY OF THE INVENTION
The present invention provides a liposome composition whose liposome membrane comprises a polyoxyethylene derivative represented by the general formula: anion-forming group, and n is an integer of 2 to 50, and a phospholipid.
DETAILED DESCRIPTION OF THE INVENTION
Regarding the above polyoxyethylene derivative, the alkanoyl group represented by X is preferably C.sub.5-30 straight or branched chain alkylcarbonyl and examples thereof include valeryl, isovaleryl, pivaloyl, lauroyl, myristoyl, palmitoyl, stearoyl and the like. Among them, C.sub.12-20 straight-chain alkanoyl groups are especially preferred. The alkyl group represented by X is preferably C.sub.5-30 straight or branched chain alkyl and examples thereof include pentyl, hexyl, octyl, decyl, dodecyl (lauryl), tridecyl, hexadecyl (cetyl), octadecyl, eicosyl and the like. Particularly, straight-chain C.sub.12-20 alkyl groups a
REFERENCES:
patent: 4411882 (1983-10-01), Franz
patent: 4844904 (1989-07-01), Hamaguchi
patent: 5019394 (1991-05-01), Hamaguchi
patent: 5028606 (1991-07-01), Venet
Iga Katsumi
Ogawa Yasuaki
Ohkouchi Kazuhiro
Kishore G. S.
Page Thurman K.
Takeda Chemical Industries Ltd.
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