Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
1994-02-14
2001-03-20
Harrison, Robert H. (Department: 1619)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C424S489000, C424S499000, C424S501000, C514S951000
Reexamination Certificate
active
06203802
ABSTRACT:
The present invention relates to a composition for the cosmetic and/or pharmaceutical treatment of the upper layers of the epidermis, by topical application of the said compositicn to the skin, and a preparation process for obtaining it.
It is well known in cosmetics and/or in pharmacy to apply to the skin oils which are active and/or which contain an active ingredient. These oils are used as they are or, more often, in the form of a water-in-oil or oil-in-water emulsion. These oils are known to have an action on the surface of the skin, but also in the upper layers of the epidermis, since they pass through the stratum corneum, the cosmetic and/or pharmaceutical action of the oils generally increasing in efficacy with an increase in the proportion of oil penetrating into the upper layers of the epidermis.
Moreover, nanoparticles are known: this name is used to denote colloidal particles of the order of 10 to 1,000 nm in size consisting of polymeric materials, in which an active principle is trapped, encapsulated and/or adsorbed (see J. KREUTER, J. MICROENCAPSULATION 1988, Vol. 5, pages 115-127). The term nanoparticles can be used to denote nanospheres and nanocapsules: a nanosphere constitutes a porous solid polymer matrix on which the active ingredient is adsorbed; a nanocapsule is a polymer membrane surrounding a core consisting of the active principle. For the remainder of the description and in the claims, the scope of the term “nanoparticles” will be strictly limited to nanocapsules defined above. Among polymers which may be used for the manufacture of nanoparticles, biodegradable materials are preferably selected in order to enable the said nanoparticles to be used therapeutically. It is known that cyanoacrylates, and especially polyalkyl cyanoacrylates, enable biodegradable nanoparticles to be obtained; the preparation of nanoparticles from cyanoacrylates is described in EP-B-0,007,895 and EP-B-0,064,967.
The use of biodegradable nanoparticles encapsulating biologically active compounds has been proposed in many therapeutic applications for many active principles, such as antimitotic or antineoplastic substances, antibiotics, hormonal substances, insulin, heparin or biological products such as proteins, antigens or the constituents of viruses, bacteria or cells. It has hence already been proposed to administer nanoparticles encapsulating active principles orally, subcutaneously, intradermally, intramuscularly, intravenously and by application to the eye (see EP-B-0,007,895, EP-B-0,064,967, FR-B-2,604,903, DE-A-3,722,837, DE-A-3,341,001 and FR-B-2,304,326).
In FR-A-2,515,960, nanoparticles of cyanoacrylate encapsulating an oil or an active substance dispersed in an oil have been described, and it is specified that these nanoparticles can be administered orally, subcutaneously, intradermally, intramuscularly or intravenously. In addition, in this document, the use of nanoparticles for encapsulating perfumes has been described, the encapsulated perfumes having the advantage of causing the perfume odor to persist longer after application than in the case where the perfume is applied to the skin without encapsulation; encapsulation hence has a delay action on the perfume. In addition, in this case, the desired action of the perfume takes place at the surface of the skin, and the persistence of the odor is completely independent of the fate of the fraction of the nanoparticles which might possibly pass through the stratum corneum. This topical application hence provides no information as to the possible capacity of the nanoparticles to pass through the stratum corneum and to be degraded in the upper layers of the epidermis; it leads, on the contrary, to the prediction that the nanoparticles would remain predominantly at the surface of the skin, since they permit release of the perfume.
According to the present application, it was found that, by cutaneous topical application of a composition comprising biodegradable nanoparticles encapsulating oils which are active and/or which contain an active ingredient, an especially effective cosmetic and/or pharmaceutical action was obtained.
The improvement in the cosmetic and/or pharmaceutical efficacy of the oils as a result of encapsulation in nanoparticles could in no way be foreseen; it was not obvious, in effect, on the one hand that the nanoparticles would pass through the stratum corneum more readily than the unencapsulated oil, whether the latter is in the form of a water-in-oil or oil-in-water emulsion, and on the other hand that these nanoparticles would be biodegraded in the upper layers of the epidermis. It was known, admittedly, that the proposed forms for administration in the human body, especially by injection, lead to biodegradation of the nanoparticles in the different tissue regions in which they are introduced. However, it is well known that different tissues have different constitutions and contain different enzymes; in particular, it is well known that the connective tissue of muscle, dermis and the deep layers of the skin, where the nanoparticles had previously been introduced by injection, have a very different biochemical constitution from that of the upper layers of the epidermis (see, for example, British Journal of Dermatology (1976) 94, 443).
Hence, nothing enabled those skilled in the art to anticipate that the nanoparticles were, on the one hand capable of passing through the stratum corneum in significant amounts, and on the other hand capable of releasing the active ingredient very rapidly into the upper layers of the epidermis.
According to the present invention, it was found, in addition, that the encapsulation of an active oil (or one containing an active ingredient) in nanoparticles produced, surprisingly, an immediate action of the composition. The delay effect reported for the perfuming compositions applied topically in the document FR-A-2,515,960 cited above led those skilled in the art to anticipate that a topical application, assuming it to be capable of having an effect, could have only a delayed action. The invention hence proposes a composition whose properties are unexpected. Moreover, these properties are especially well suited to topical administration, as was shown in a comparative in vitro study of percutaneous absorption.
The subject of the present invention is consequently a composition for the cosmetic and/or pharmaceutical treatment of the upper layers of the epidermis, by topical application to the skin, characterised in that it comprises, in a suitable vehicle, biodegradable polymer nanoparticles encapsulating at least one active ingredient in the form of an oil and/or at least one active ingredient contained in an inactive carrier oil or an active oil, the active ingredient being selected from those having a cosmetic and/or pharmaceutical action.
The nanoparticles used are preferably between 10 and 1000 nm, and more especially between 50 and 500 nm, in size.
The weight of the nanoparticles loaded with at least one active ingredient advantageously constitutes from 0.1% to 20% of the total weight of the composition, and preferably from 0.5 to 5%. by weight.
The polymers constituting the biodegradable nanoparticles can be polymers of C
2
-C
12
, and especially C
2
-C
6
, alkyl cyanoacrylate; the alkyl radical is preferably selected from the group composed of ethyl, n-butyl, hexyl, isobutyl and isohexyl radicals. The biodegradable polymers may also be taken from the group composed of poly-L-lactides, poly-DL-lactides, polyglycolides, polycaprolactones, polymers of 3-hydroxybutyric acid and the corresponding copolymers, such as copoly(DL-lactides/glycolides), copoly(glycolides/caprocolatones) and the like.
The use of nanoparticles obtained from poly-L-lactides, poly-DL-lactides and copoly(DL-lactides/glycolides) is especially advantageous, since the products of enzymatic or chemical biodegradation of these nanoparticles can themselves have cosmetic effects: thus, lactic acid exhibits humectant and plasticising properties; and glycolic acid exhibits depigmenting and/or biostimulatory
Handjani Rose-Marie
Ribier Alain
Harrison Robert H.
L'Oreal
Nixon & Vanderhye P.C.
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