Anti-microbial body care product

Details Anti-microbial body care product Anti-microbial body care product

2001-12-14

2004-04-13

Page, Thurman K. (Department: 1615)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Matrices

C424S400000, C424S402000, C424S404000, C424S443000, C424S444000, C424S447000, C424S486000, C424S487000, C424S489000

Reexamination Certificate

active

06720006

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a body care product having anti-microbial activity, especially an anti-microbial disposable absorbent article, toothbrush, cosmetic product or baby comforter.
BACKGROUND OF THE INVENTION
Body care products are products which are brought into contact with human or animal skin and/or mucosa to provide a cleaning, protective, therapeutic, cosmetic benefit or soothing. Such products, for example disposable absorbent articles, such as diapers, incontinence articles, catamenial devices, training pants, panty liners, toothbrushes or baby comforters etc. normally comprise surfaces contacting the skin made of a natural or often synthetic polymeric material, or skin care compositions such as emulsions, lotions, creams, ointments, salves, powders, suspensions, gels, soaps, etc. Said products comprise either a polymer or an organic component in the carrier base, which is a good substrate for a number of microorganisms. The growth of such microorganisms on theses substrates may cause hygienic and medical problems.
It is already known to impregnate or coat such solid substrates with anti-microbial agents or disinfectants or to incorporate such active agents into said cosmetic bases to provide an anti-microbial activity. However, this method has only been a partial success. Continued sub-inhibition of chemically active substances induces resistance to microorganisms and thus, sensibilisation. The efficacy is limited to a certain range of germs and the activity is only of short-term.
It is already known as well to use silver in various forms as an anti-microbial agent, however, it is a serious problem to find the most appropriate delivery system.
For example there have been numerous attempts incorporate silver into various polymer articles, such as pipes, medical components, films, fibers, with varying degrees of success. For example this technology is subject-matter of U.S. Pat. No. 5,180,585, which discloses an anti-microbial composition comprising an inorganic particle with a first coating providing anti-microbial properties and a second coating providing a protective function.
European patent number EP0711113 discloses a process for producing bactericidal/fungicidal plastic bodies which comprises coating a plastic blank with one or more anti-microbially active metal(s) and/or metal compound(s) by means of a chemical or physical process, then grinding and/or melting said coated blank and finally imparting the desired shape to said material. In this way medical catheters of polyurethane comprising silver particles having a particle size below 100 nm, preferably of 10 nm, in an amount of not more than 1.0% by weight have been made.
However, it has also been found that silver ions while having an anti-microbial and anti-fungal activity are problematic once they are kept for a longer time at a high concentration in contact with the human skin or mucosa, because of their potential cytotoxicity.
The problem underlying the present invention therefore is to provide for a body care product that can be kept in contact with the human or animal skin or mucosa for a longer time during its normal use and which provides the desired anti-microbial activity without detrimental effects on the person using that product.
SUMMARY OF THE INVENTION
The above problems are solved by the body care product invention disclosed and claimed herein and by the preferred embodiments thereof, namely disposable absorbent articles, toothbrushes, cosmetic products and baby comforters.
Subject-matter of the present invention, therefore, is an anti-microbial body care product comprising in the part contacting human or animal skin and/or mucosa an organic matrix containing homogeneously dispersed particles of metallic silver having a particle size in the range of 1 to 50 nm (in the following termed “silver nanoparticles”) in an amount providing on the surface of said part an anti-microbially effective but less than cytotoxic silver concentration.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
It has been surprisingly found that a body care product comprising a surface contacting human or animal skin and/or mucosa shows an excellent tissue compatibility by not providing any cytotoxicity and is active against a broad range of microbes without any indication of resistance because of the very small quantities of silver released from the surface of said body care product over a long period. Based on this the body care product of the present invention is ideally suited for applications, wherein during normal use said product is in contact with the human or animal skin and/or mucosa for a longer period of time, by preventing irritation of the skin of the user and any negative changes to the skin structure.
For the purpose of the present invention, anti-microbial efficacy, i.e. activity against a broad range of microbes, may be quantified for example by methods such as described in
Der Erlanger Silberkatheter: In
-
vitro Ergebnisse zur antimikrobiellen Wirksamkeit
in Infection 26 (1998) Suppl. 1, German edition, pages 25 through 31.
For the purpose of the present invention, cytotoxicity may be quantified for example by methods such as described in
Untersuchung der akuten Zytotoxizität des Erlanger Silberkatheters zur Bestimmung der Biokompatibilität
in Infection 26 (1998) Suppl. 1, German edition, pages 36 through 39.
According to a preferred embodiment of the present invention, said silver nanoparticles are dispersed in said organic matrix in such an amount that a silver concentration of from more than 1 nmol/l to less than 1 &mgr;mol/l is provided, specifically when in contact with body fluids present on the surface of the human or animal skin and/or mucosa.
Preferably said organic matrix in contact with the human or animal skin comprises said silver nanoparticles in an amount from 1 to 2000 ppm, preferably from 5 to 1000 ppm and more preferably from 10 to 250 ppm.
The silver nanoparticles homogeneously dispersed in said organic matrix preferably have a particle size of 2 to 10 nm, more preferably of 5 to 8 nm.
The organic matrix into which said silver nanoparticles are homogeneously dispersed can be solid or fluid. The term fluid includes liquid and semisolid and covers a viscosity range of from 5 to 5000 mPa, preferably 5 to 500 mPa measured at 60° C. using a rotational viscosimeter (such as a Brookfield viscosimeter) at 60 rpm using a number 2 spindle.
In case the organic matrix is a solid material, it preferably comprises an organic polymer wherein said silver nanoparticles are homogeneously dispersed.
Said organic polymer of the solid organic matrix preferably comprises a thermoplastic resin, such as a polyamide, polyether, polyester, polyolefine, vinyl or (meth) acrylate homopolymer, copolymer or terpolymer, polyurethane and/or silicone rubber.
In incorporation of the silver nanoparticles into such polymers can be provided by making use of the method disclosed in EP0711113, supra, i.e. by coating a plastic blank with silver by means of a chemical or physical process, grinding and/or melting said coated blank and finally providing a molded article out of this polymer containing the homogeneously dispersed silver nanoparticles.
According to a further embodiment of the present invention, the part of the body care products contacting human or animal skin and/or mucosa comprises a fluid organic matrix wherein said silver nanoparticles are homogeneously dispersed. Said fluid organic matrix preferably is a viscous organic fluid having a viscosity as referred to above and comprises preferably aliphatic or aromatic hydrocarbon, a mineral oil, petrolatum, glycerol, a fatty alcohol, propylene glycol, polypropylene glycol, an animal and/or vegetable oil or fat or a silicone oil. Specifically preferred are silicone oils, i.e. polysiloxanes such as phenyl-functional-polymethylsiloxane compounds having a viscosity at 37° C. ranging from 5 to 5000 mPa, more preferably 5 to 2000 mPa, as measured with the viscosimeter preferred to above at a temperature of 37° C. A suitable silicone oil is available

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