Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Patent
1996-06-17
1998-05-12
Lovering, Richard D.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
252312, 252314, 514941, A61K 9113, B01J 1300
Patent
active
057501246
DESCRIPTION:
BRIEF SUMMARY
This application is 371 of PCT/DE94/01157 filed Oct. 1, 1994 which claims priority based on Fed. Rep. Germany P 4343833.4 filed Dec. 22, 1993.
The present invention relates to stable multiple emulsions of the W/O/W type, processes for their preparation and their use for cosmetic and medical purposes.
Cosmetic skin care is primarily to be understood as intensifying or re-establishing the natural function of the skin as a barrier against environmental influences (for example dirt, chemicals and microorganisms) and against the loss of endogenous substances (for example water, naturally occurring fats and electrolytes).
If this function is impaired, increased absorption of toxic or allergenic substances or attack by microorganisms and as a consequence toxic or allergic skin reactions may occur.
The aim of skin care is furthermore to compensate the loss of oils and water by the skin caused by daily washing. This is important in particular if the natural regeneration capacity is not sufficient. Furthermore, skin care products should also protect against environmental influences, in particular against sun and wind, and delay ageing of the skin.
Medical topical formulations as a rule comprise medicaments in an active concentration. For simplicity, reference is made to the legal provisions of the Federal Republic of Germany (for example cosmetics legislation, Foodstuffs and Medical Preparations Act) for a clear differentiation between cosmetic and medical use and corresponding products.
It is known that multiple emulsions--inter alia--can be distinguished by a particularly fine emulsion texture. This property is outstandingly suitable as a basis both for cosmetic and for medical topical formulations. However, where cosmetics are used only externally, all customary types of administration, for example oral administration forms, are conceivable for the medical use of emulsions.
In simple emulsions, finely dispersed droplets of the second phase (water droplets in W/O emulsions or lipid vesicles in OW emulsions) enclosed in an emulsifier shell are present in the first phase. In a multiple emulsion (second degree), on the other hand, more finely dispersed droplets of the first phase are emulsified in such droplets. Even more finely dispersed droplets may in turn also be present in these droplets (third degree multiple emulsion), and so on.
In the same way as W/O or O/W emulsions are referred to in the case of simple emulsions (Water-in-Oil or Oil-in-Water), there are W/O/W, O/W/O, O/W/O/W, W/O/W/O emulsions and so on in the case of multiple emulsions.
A W/O/W emulsion is shown in diagram form in FIG. 1, the shaded areas denoting the external and internal aqueous phase and the white areas the oily phase.
Multiple emulsions in which the particular internal and external aqueous phases or internal and external oily phases are different in nature (that is to say, for example, W/O/W' and O/W/O' emulsions) can be prepared by two-pot processes. Those emulsions in which the internal and external aqueous or oily phases are not different in nature are obtainable both by one-pot and by two-pot processes.
The multiple emulsions of the second degree are occasionally called "bimultiple systems", those of the third degree are occasionally called "trimultiple systems" and the like (W. Seifriz, Studies in Emulsions, J. Phys. Chem., 29 (1925) 738-749).
Processes for the preparation of multiple emulsions are familiar per se to the expert. Thus, there are two-pot processes in which a simple emulsion (for example a W/O emulsion) is initially introduced into the reaction vessel and is converted into a multiple emulsion (for example a W/O/W emulsion) by addition of another phase (for example an aqueous phase) with a corresponding emulsifier (for example an O/W emulsifier).
A second process comprises converting emulsifier mixtures with an oily phase and an aqueous phase into a multiple W/O/W emulsion in a one-pot process. The emulsifiers are dissolved in the oily phase and combined with the aqueous phase. A prerequisite for such a process is th
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McCutcheon's Detergents and Emulsifiers, No. American Edition/1973, p.113,
Gohla Sven
Muller Anja
Nielsen Jens
Beiersdorf AG
Lovering Richard D.
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