Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
2000-03-09
2002-01-08
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C424S070100, C424S059000, C424S062000, C424S063000, C514S369000, C514S844000, C514S937000
Reexamination Certificate
active
06337077
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a composition with a continuous aqueous phase containing L-2-oxothiazolidine-4-carboxylic acid.
2. Background of the Invention
L-2-oxothiazolidine-4-carboxylic acid, or procysteine, is known as a component of cosmetic or dermatological compositions intended for topical application to the skin. Such compositions can be intended for preventing hair loss or for stimulating the regrowth of hair, as described in EP 656 201. Procysteine is also known from patent FR 2 742 658 as an agent for depigmenting or bleaching human skin.
However, procysteine has a certain level of instability, in particular when it is in the presence of water. Thus, when it is introduced into a cosmetic composition, in particular a composition comprising water, its efficacy decreases over time. In addition, after storage for a certain period, the composition into which it is introduced shows signs of degradation: coloration, odor, which users find unacceptable. One solution for stabilizing procysteine in water consists in combining it with a polyol, in specific amounts by weight, and in limiting the amount of water to a value of 35% by weight, and preferably less than 20% by weight, relative to the total weight of the composition.
Although these compositions do in effect make it possible to convey procysteine stably over time without any loss of efficacy of this active agent, not all users necessarily find their texture suitable and the need remains for compositions capable of containing large amounts of water, for example greater than 80% by weight, in particular in the form of oil-in-water emulsions.
Admittedly, compositions in the form of oil-in-water emulsions containing procysteine are known from EP 656 201, but the Applicant has observed that these compositions were not stable over time and led to a degradation of the procysteine, resulting in the development of a nauseating sulphureous odor and yellowing of the composition.
SUMMARY OF THE INVENTION
The Inventors have now found that the use, in combination, of a sequestering agent and a neutralizing agent in an amount which is sufficient to adjust the pH of the composition to a value of between 5 and 8 makes it possible to formulate procysteine in compositions with a continuous aqueous phase which remain stable over time and/or with the temperature.
Accordingly, the present invention provides a composition, comprising:
a continuous aqueous phase comprising L-2-oxothiazolidine-4-carboxylic acid, at least one sequestering agent and at least one neutralizing agent, wherein the pH of the aqueous phase is 5 to 8.
The composition obtained is stable, in particular with respect to thermal degradation, and also at water contents ranging up to 97% by weight, which makes it particularly suitable for cosmetic or dermatological applications.
The present invention also provides a method of preparing the composition described above by combining water, L-2-oxothiazolidine-4-carboxylic acid, the sequestering agent and an amount of at least one neutralizing agent effective to adjust the pH of the continuous aqueous phase to 5 to 8.
The present invention also provides a composition obtained by combining water, L-2-oxothiazolidine-4-carboxylic acid, at least one sequestering agent and an amount of at least one neutralizing agent effective to adjust the pH of the composition to 5 to 8.
The present invention also provides a method of stabilizing L-2-oxothiazolidine-4-carboxylic acid in a composition containing a continuous aqueous phase, comprising incorporating into the composition at least one sequestering agent and at least one neutralizing agent, wherein the neutralizing agent being present in an amount which is sufficient to adjust the pH of the aqueous phase of the composition to a value of between 5 and 8.
The present invention also provides a method of depigmenting or bleaching the skin, body hairs and/or head hair, comprising applying the inventive composition to the skin, body hairs and/or head hair.
The present invention also provides a method of preventing hair loss and/or for stimulating regrowth of the hair, comprising applying the inventive composition to the hair.
The present invention also provides a method of preventing or treating light-induced ageing and/or environment-related stress of the skin, comprising applying the inventive composition to the skin.
The present invention also provides method of preventing or treating greasy skin, comprising applying the inventive composition to the skin.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description.
DETAILED DESCRIPTION OF THE INVENTION
Preferably, the composition according to the invention comprises from 0.01 to 10% by weight, preferably from 0.1 to 5% and even more preferably from 0.5 to 3% by weight, of L-2-oxothiazolidine-4-carboxylic acid relative to the total weight of the composition. These ranges include all specific values and subranges therebetween, such as 0.02, 0.05, 0.2, 1,2 and 8% by weight.
The terms “L-2-oxothiazolidine-4-carboxylic acid” or “procysteine” refer to either the acid form or the carboxylate, since, as will be readily appreciated by one skilled in the art, in an aqueous medium of pH 5 to 8 there will be at least a portion of the carboxylate form of the compound. As will be readily appreciated, the carboxylate will be ion-paired with a cation, for example from the neutralizing agent.
The neutralizing agent used in the composition according to the invention can be chosen in particular from: alkali metal hydroxides, such as sodium hydroxide and potassium hydroxide; ammonia; organic bases such as monoethanolamine, diethanolamine, triethanolamine, aminomethyl-1,3-propanediol, N-methylglucamine and basic amino acids such as arginine and lysine; and mixtures thereof. The neutralizing agent is preferably triethanolamine.
The neutralizing agent is present in an amount which is sufficient to adjust the pH of the aqueous phase of the composition to between 5 and 8, preferably between 6 and 7. To do this, a person skilled in the art can readily adjust the amount of neutralizing agent as a function of the acids, other than the L-2-oxothiazolidine-4-carboxylic acid, which may be present in the composition according to the invention and as a function of the nature of the neutralizing agent. For example, when the composition according to the invention contains no acid other than L-2-oxothiazolidine-4-carboxylic acid and when the neutralizing agent used is triethanolamine, the weight ratio of the neutralizing agent to the L-2-oxothiazolidine-4-carboxylic acid is generally between 0.7:1 and 1.3:1, better still between 0.9:1 and 1.2:1. According to one preferred embodiment of the invention, the weight ratio of the neutralizing agent to the L-2-oxothiazolidine-4-carboxylic acid is 1:1.
The sequestering agent combined with the neutralizing agent can be chosen in particular from: EDTA; EDTA salts such as the disodium and tetrasodium salts of EDTA or the dipotassium salt of EDTA; disodium cocoamphodiacetate; diethylenetriamine pentaacetic acid and its salts, such as the pentasodium salt of diethylenetriamine pentaacetic acid; the trisodium salt of nitrilotriacetic acid; ascorbic acid; trisodium citrate; etidronic acid and its salts, such as the tetrasodium salt of etidronic acid; the heptasodium salt of diethylenetriamine pentamethylene phosphonic acid; the pentasodium salt of diethylenetriamine tetramethylene phosphonic acid; ethylenediamine tetramethylene phosphonic acid and its salts, such as the pentasodium salt of ethylenediamine tetramethylene phosphonic acid; sodium glucoheptanoate; and mixtures thereof. Preferably, the sequestering agent is an EDTA salt.
The sequestering agent is present, for example, in an amount of between 0.01 and 1% by weight, preferably between 0.01 and 0.5% by weight, and better still in an amount of about 0.05% by weight, relative to the
Chevalier Veronique
Quest Mélanie
Page Thurman K.
Seidleck Brian K.
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