Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Liposomes
Patent
1993-10-14
1995-08-22
Kishore, Gollamudi S.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Liposomes
4284022, 424401, 514944, A61K 9127
Patent
active
054438403
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a cosmetic and/or pharmaceutical composition containing a transparent dispersion of ionic and/or nonionic amphiphilic lipid vesicles, to a process for the preparation of said dispersion and to a new dispersion used in the said composition.
It is known that it is possible to prepare vesicles from certain amphiphilic lipids, that is to say from molecules consisting of a lipophilic part and of a hydrophilic part. The vesicles obtained are delimited by a lipid phase membrane formed from a sheet or a number of concentric sheets, the said membrane defining a closed internal volume where a phase, known as encapsulated phase, is encapsulated. The vesicles are generally prepared in the form of a dispersion in an aqueous phase, known as the dispersion phase. The amphiphilic lipids can be ionic lipids such as natural lecithins (egg lecithin, soya lecithin) or synthetic lecithins (dipalmitoyllecithin, hydrogenated egg lecithin). The amphiphilic lipids can also be nonionic lipids such as linear or branched polyglycerol derivatives, linear or branched polyglycerol ethers, polyoxyethylenated fatty alcohols, polyoxyl-ethylenated sterols, polyol ethers, oxyethylenated or nonoxyethylenated polyol esters, glycol lipids, certain hydroxyamides and others.
The lipid phase can contain one or a number of ionic amphiphilic lipids, one or a number of nonionic amphiphilic lipids or, at the same time, at least one ionic amphiphilic lipid and at least one nonionic amphiphilic lipid.
It is known to introduce into the lipid phase at least one lipophilic cosmetically and/or pharmaceutically active principle, the nature and the amount of the reactants introduced being chosen so as not to damage the stability of the vesicles. It is also possible, in a known way, to introduce hydrophilic active principles into the encapsulated aqueous phase and/or into the aqueous dispersion phase.
For reasons of presentation, the search is to prepare dispersions of vesicles which are substantially transparent, because the cosmetic compositions prepared from transparent dispersions have a more pleasant and more attractive appearance for the user.
The transparency (or, conversely, the opaqueness) of a dispersion, with respect to natural light, is essentially a function of the refractive index of the dispersion medium and of that of the dispersion particles, of the concentration, of the mean size and of the size homogeneity of these particles. It is especially possible to increase the transparency of a dispersion by reducing the difference between the refractive index of the dispersed particles and that of the dispersion medium and/or by reducing the concentration and/or the size of the dispersed particles. Of course, it is possible to improve the transparency of a dispersion of lipid vesicles by diluting this dispersion but the concentration of active principles in the dispersion would thus be reduced, which generally has to be avoided. It has also been attempted to reduce the mean size of the vesicles, but it is then necessary to use, for an excessively long time, during the preparation of the vesicles, powerful mechanical means such as pressure homogenizers or ultrasound, which leads to a higher cost price. It was also considered to reduce the polydispersity by using grading methods such as pressure filtration or size fractionation using chromatography columns, but these methods are restricting and expensive.
According to the present invention, it was found that the transparency of dispersions of vesicles in which the lipid phase contains at least one ionic amphiphilic lipid and/or at least one nonionic amphiphilic lipid is considerably improved by introducing, into the said lipid phase, at least one polyol or one isoprenoic acid containing a phytyl chain, without it being necessary to modify the method of preparation of the vesicles. It was observed that even dispersions having a high lipid concentration, for example a concentration greater than 5% by weight, are then substantially transparent.
The first subject of the pre
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Lety Alain
Morancais Jean-Luc
Vanlerberghe Guy
"L'Oreal"
Kishore Gollamudi S.
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