Drug – bio-affecting and body treating compositions – Topical body preparation containing solid synthetic organic... – Skin cosmetic coating
Reexamination Certificate
2000-04-25
2002-04-16
Sellers, Robert E. L. (Department: 1712)
Drug, bio-affecting and body treating compositions
Topical body preparation containing solid synthetic organic...
Skin cosmetic coating
C424S401000, C523S337000
Reexamination Certificate
active
06372204
ABSTRACT:
The present invention relates, on the one hand, to a topical composition, which is useful in particular in cosmetics and in dermopharmacy, comprising an aqueous phase and a thickener, and, on the other hand, to a novel thickener in its normal state, which is well tolerated by the skin and mucosae.
Patent application EP-A-0,424,260 and international application WO 92/21316 describe cosmetic compositions or compositions for treating keratinous material which may comprise an ammonium acrylate/acrylamide copolymer dispersed in a water-in-oil emulsion. This dispersion comprises oleosoluble surfactants having a hydrophilic/lipophilic balance (or HLB) of less than 7. It is useful as a thickener. The Applicant has, however, been able to observe that this type of thickener, in the form of a dispersion, is poorly suited to the preparation of certain compositions, such as emulsions comprising at least one oil phase and at least one aqueous phase. The reason for this is that this type of thickener is difficult to mix with the polar oils liable to constitute the oil phase of these emulsions.
Patent application EP-A-0,503,853 describes topical compositions, that is to say compositions intended to be applied to human or animal skin or mucosae, comprising a thickener consisting of a water-in-oil reverse emulsion and a copolymer. The copolymer is essentially in solution in the aqueous phase constituting the said reverse emulsion. The copolymer consists of units derived (a) from a monoacrylamide monomer, (b) from a 2-acrylamido-2-methylpropanesulphonic (AMPS) acid monomer and (c) from a polyfunctional monomer. Such a thickener has the advantage of being able to invert itself when it is diluted in a hydrophilic phase. Thus, when the thickener which comprises a water-in-oil reverse emulsion is mixed with the other components forming the said topical composition, the sense of the emulsion is reversed, such that the aqueous phase becomes continuous. This thickener is entirely suitable for the preparation of topical compositions comprising, in particular, polar oils with which it is fully miscible. The thickener also has the advantage of being relatively well tolerated by the skin tissues and mucosae on which it is applied.
However, the Applicant has been able to observe that the thickeners used in the topical compositions according to patent application EP-A-0,503,853 could not conveniently be used for the manufacture of all types of topical compositions. Thus, it may be difficult to prepare fluid emulsions, thickened by thickeners of this type, in a reproducible manner in terms of viscosity. “Fluid emulsions” is understood here to refer to topical compositions having a viscosity of less than about 25 Pa s (Brookfield, LV4, 6 revolutions/minute). The reason for this is that topical compositions of this type require relatively low contents of the said thickener. Now, on account of the nature of the latter, slight variations in the thickener concentrations used may lead to considerable variations in the viscosity of the topical composition. It is thus difficult to prepare topical compositions with such a thickener in a reproducible manner on an industrial scale.
It has also been observed that the viscosity-modifying effect afforded by the thickener described in the above document is reduced when this thickener is combined in the topical composition with electrolytes, such as sodium chloride or magnesium chloride.
Moreover, patent application EP-A-0,186,361 describes thickeners which are useful for preparing pasty printing inks. The thickener consists in particular of a water-in-oil emulsion comprising an aqueous phase in which is dissolved a homopolymer or copolymer based, preferably, on moieties derived from acrylic acid. Like the thickener described in EP-A-0,503,853, this thickener is prepared according to the process, which is known per se, of reverse emulsion polymerization. According to this process, the polymerization of monomers is performed in a water-in-oil emulsion. The oil phase constituting this emulsion is usually based on a volatile oil, such as an isoparaffin oil. However, the Applicant has observed that-this thickener was not well tolerated by the skin.
The Applicant has thus developed a topical composition which constitutes a first subject of the invention, circumventing the abovementioned drawbacks of topical compositions. More particularly, the topical composition according to the invention comprises a thickener based on a reverse emulsion, which is well tolerated by the tissues on which it is applied, and which moreover has a viscosity which is stable even in the presence of electrolytes.
According to another aspect, the invention relates to topical compositions, in particular fluid emulsions, comprising a thickener, it being possible for the said topical composition to be readily prepared in a reproducible manner on an industrial scale.
According to yet another aspect, the invention relates to a thickener comprising a copolymer, which may readily be used for thickening and emulsifying a topical composition comprising a reverse emulsion, the said thickener making it possible to obtain very good tolerance with respect to the tissues on which it is applied.
The present invention thus relates to a topical composition comprising at least one aqueous phase, a non-volatile oil and a thickener, characterized in that the thickener is chosen from those comprising a water-in-oil reverse emulsion and a copolymer having moieties derived (i) from a monounsaturated monocarboxylic acid monomer containing from three to five carbon atoms, the monocarboxylic acid either being in free form or in the form of an inorganic salt, and (ii) from a monoacrylamide monomer, the copolymer being in solution in the aqueous phase constituting the reverse emulsion and the oil phase of the reverse emulsion comprising at least one volatile oil.
Within the context of the present invention, it is clearly understood that the sense of the emulsion constituting the thickener is the sense existing prior to the mixing of this thickener with the other components constituting the topical composition, in particular the hydrophilic components. Thus, it is notable that the thickener, in accordance with the invention, comprising a water-in-oil reverse emulsion, may invert to form an emulsion in which the continuous phase is an aqueous phase, this inversion taking place during dilution of the thickener with a hydrophilic phase constituting the topical composition.
After inversion, the copolymer is released into the continuous phase and thereby imparts increased viscosity thereto.
Other aspects of the present invention will emerge from the description which follows and from the FIGURE.
The FIGURE represents the viscosity, measured by a Brookfield LV4 viscometer rotating at 6 revolutions/minute, of a topical composition obtained using increasing concentrations of a thickener in accordance with the invention, compared with the viscosity of a similar topical composition of the prior art, also comprising a thickener.
The Applicant has observed that a topical composition comprising a non-volatile oil as well as a thickener as described above was perfectly tolerated by the tissues on which it was applied.
The non-volatile oil present in the topical composition may be a constituent, at least in part, of the oil phase of the reverse emulsion forming the thickener. This oil phase thus consists essentially of a mixture of at least one volatile oil and at least one non-volatile oil. In this case, the weight ratio between the volatile oil and the non-volatile oil in the water-in-oil reverse emulsion forming the thickener is usually between 90/10 and 10/90, preferably between 30/70 and 70/30.
The weight ratio between the non-volatile oil and the volatile oil in the topical composition in accordance with the invention is usually greater than 0.5:1, preferably greater than 0.9:1 and more generally between 1.1 and 100:1.
Within the context of the present invention, in order to determine whether or not an oil is volatile, the following test is
Amalric Chantal
Michel-Lecocu Nelly
Sellers Robert E. L.
Societe d'Exploitation de Produits pour les Industries Chim
Young & Thompson
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