Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Particulate form
Reexamination Certificate
2000-04-21
2002-08-13
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Particulate form
C424S489000, C424S484000, C424S501000
Reexamination Certificate
active
06432451
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a method for film coating the surface of porous micro beads having pores containing active components with silicone or its derivatives, and cosmetic and pharmaceutical compositions for dermal application containing porous micro beads silicone-coated by the film coating method.
2. Description of the Related Art
Ingredients such as vitamins, antioxidants and enzymes are known to have effects of, for example, whitening, wrinkle clearing, increasing skin's elasticity, noxious oxygen removing, etc. and have been widely used as active components of cosmetic and pharmaceutical compositions for dermal application. However, when exposed to light or air, the active components are susceptible to oxidation and destruction and thus limited in their applications. Oxidation of the active components causes not only a deterioration of potency but also discoloration, for example, browning or yellowing depending on the type of the active components.
Such an oxidative destruction accelerates for active components that are present in an aqueous phase or in contact with water.
In connection to this, there have been suggested a number of methods for stabilization of the active components by minimizing contact of the active components with water.
A method for formulating active components into dry powder (see. Japanese Patent Application Laid-open So 63-130514) is effective in maintaining stability of the active components to a certain extent but confined in formulation to powder. Thus the method is inapplicable to general cosmetic compositions of which the typical formulation is emulsion.
In an alternative method to cope with the problem, two separate containers are packed with powdery active components and an emulsified cosmetic liquid, respectively, for the user to mix prior to application (see. U.S. Pat. No. 4,818,512). However, this method is problematic in regard to inconvenience for the user who has to mix the contents of the two containers before use, and high expense of the packages.
An anhydrous formulation containing no moisture (see. U.S. Pat. No. 5,322,683) may retain stability of active components but is confined to powder. Also, the anhydrous formulation gives an unpleasant feeling to the skin because of its greasy property and is especially inapplicable to water soluble active components.
There have been proposed further another methods involving addition of polyhydric alcohols such as glycerin, or other organic solvents compatible with water (see. U.S. Pat. Nos. 5,703,041 and 4,983,382; JP Patent No. 44-22312; and U.S. Pat. No. 4,372,874). These methods stabilize the active components to a certain extent but give an unpleasant feeling to the skin due to its stickiness peculiar to polyhydric alcohols. Especially, organic solvents useful for stabilization of the active components, such as dimethylsulfoxide are normally toxic to the human body.
Besides, a method has been reported to utilize microcapsules and stabilize active components with a physical layer formed on the outer surface of the active components (Simon Benita (ed), 1996, Microencapsulation: Methods and industrial applications, Marcel Dekker, Inc. New York). The microcapsules are however unsatisfactory to achieve complete stabilization of the active components, because the coating on the wall material constituting the microcapsules permits entrance of water and allows active components to dissolve out through diffusion.
An alternative method involves retaining active components in the pores of porous microbeads in the same manner as the previously stated microcapsules (William Klein and Alfred DiSapio, 1989, HAPPI magazine, 26:7; U.S. Pat. No. 5,145,675). In contrast to the microcapsules where the capsule constituents provide a complete physical separation of the internal phase of the capsules from the external one, the porous microbeads have the internal phase in communication with the external one through pores containing active components.
SUMMARY OF THE INVENTION
One aspect of the present invention provides a composition for use in dermal application. The composition comprises a plurality of particles having an internal structure of pores, a chemical compound contained in the internal structure of the porous particles, and a layer of coating over each of the particles, containing at least one of a silicone and a polysiloxane-based compound.
Another aspect of the present invention provides a method of making a composition. The method comprises the steps of: preparing a plurality of particles containing a chemical compound in an internal structure thereof; preparing a coating mixture comprising at least one of a silicone and a polysiloxane-based compound with a solvent; mixing the plurality of particles with the coating mixture, whereby the coating mixture covering over the particles; and evaporating the solvent from the coating mixture covering over the particles.
DETAILED DESCRIPTION OF THE INVENTION
In the microbead system retaining active ingredients within the pores, the stability and efflux of the active ingredients significantly depend upon their physiochemical properties and the ambient solvent constituting the internal phase as well as those of the outer base constituting the external phase due to communication between internal and external phases. For example, if the active components adsorbed in the pores or the solvent dissolving the active components within the pores have high affinity to the base of the external phase, the active components are susceptible to effusion and their stability deteriorates significantly. Thus, the internal phase of the pores must not have affinity to the base of the external phase in a composition containing active components.
Especially, in order to stabilize active components susceptive to water, the active components must have minimized contact with water while they are contained in the pores. However, a general cosmetic composition has the formulation of emulsion containing a large amount of surfactant such that two solvents naturally immiscible with each other, such as water and oil, are mixed together in no small amount. Thus, the stability of the active components in a cosmetic composition actually depends upon the physiochemical properties of the active components and the external base.
According to one aspect of the present invention, active ingredients of a cosmetic or pharmaceutical composition are retained in the internal structure of porous particles or microbeads. Thereafter, the particles or microbeads containing the active ingredients are coated with a thin film of a material.
First, active ingredients of a cosmetic or pharmaceutical composition are dissolved in a solvent selected from the group consisting of methanol, ethanol, glycerin alone, and mixtures thereof. The resulting solution or suspension is subject to physical contact with porous particles or microbeads to retain the active components in their internal structure of pores. The porous microbeads retaining the active components are separated from the solution or suspension by filtration. The residual solvent of the microbeads is removed and the active components impregnated within the internal structure of the microbeads by subsequent vacuum drying and washing processes.
The porous particles or microbeads have an internal structure of interconnected matrix structure, in which the active components are retained or impregnated. The active ingredients effuse from internal structure by capillary action when the porous particles or microbeads are applied to skin or other surfaces.
The porous microbeads usable in the present invention are prepared through formation of pores with three-dimensional cross-links of a polymer or copolymer. Examples of the polymer or copolymer include, but are not limited to polymethacrylic acid copolymer, polymethylmethacrylic acid copolymer, allyl-polymethacrylic acid copolymer, polystyrene polymer, polyethylcellulose polymer, and silicagel. All the polymers or copolymers are com
Choi Moon Jae
Guan Soon Sang
Kim Jin Han
Kim Yu Chang
Lee Jang Young
Fubara Blessing
Knobbe Martens & Olson Bear LLP.
Pacific Corporation
Page Thurman K.
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