Drug – bio-affecting and body treating compositions – Dentifrices
Reexamination Certificate
2000-06-21
2001-10-23
Rose, Shep K. (Department: 1614)
Drug, bio-affecting and body treating compositions
Dentifrices
C424S058000, C424S641000, C424S643000, C514S974000
Reexamination Certificate
active
06306372
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to mouth rinses and dentrifices which ordinarily impart a harsh taste and astringency to the mouth. More particularly, the invention relates to eucalyptol and zinc containing oral hygiene compositions wherein the burning sensation and astringency of such products is masked.
2. Description of Related Art
Mouth rinses, especially mouth washes, containing essential oils are well-known in the art of oral hygiene. For example, U.S. Pat. No. 4,945,087 is believed to be directed to the commercial product known as COOL MINT LISTERINE®. U.S. Pat. No. 4,945,087 teaches a mouth wash comprising the essential oil known as thymol which is utilized for its antimicrobial activity. The patent teaches that the thymol imparts a harsh or medicine-like taste to mouth rinses and that it would be desirable to mask this taste. For this purpose, the patent utilizes a composition containing a mixture of sugar alcohols and anethole. As an optional ingredient in the mouth rinses disclosed by U.S. Pat. No. 4,945,087, a large number of different types of surfactants are mentioned. One type of non-ionic surfactant mentioned as an optional ingredient is an ethoxylated hydrogenated castor oil (col. 4, lines 32-46), however, there is no teaching of any function of this material other than for its known function as a surface active agent (ie., surfactant). It is only through the use and manipulation of the sugar alcohols and the anethole that masking of the thymol taste is taught to be accomplished.
Another component of the commercial mouthwash LISTERINE®which is effective for its antimicrobial activity is eucalyptol (see U.S. Pat. No. 4,945,087, col. 3, lines 4-14 which discloses the possibility of using eucalyptol in addition to thymol). U.S. Pat. No. 4,945,087 attributes the harsh or medicinal taste of the product exclusively to thymol. Eucalyptol is not blamed by the patent as being responsible for or contributing to this problem. Although not appreciated or recognized by U.S. Pat. No. 4,945,807, it was subsequently discovered by the present inventors that the burning sensation of LISTERINE® is principally due to the eucalyptol, rather than the thymol. Accordingly, proposed solutions for masking the taste of thymol, such as the one taught in U.S. Patent 4,945,087, have not proved to be particularly effective for masking the burning sensation of eucalyptol containing mouth rinses such as LISTERINE®.
Another common antimicrobial agent used in oral hygiene rinses is zinc, typically added as a zinc salt. For example, European Patent Publication 0 251 542 teaches a mouth wash containing zinc chloride. However, the zinc salt is known to impart undesirable astringency to the mouth rinse. In order to abate the astringency, European Patent Publication 0 251 542 teaches the use of 0.1% to 5% by wt. polyoxyethylene hydrogenated castor oil. However, European Patent Publication 0 251 542 is not directed to eucalyptol containing mouth rinses, and the reference does not teach any means for masking the burning sensation imparted by eucalyptol containing mouth rinses.
SUMMARY OF THE INVENTION
It has been discovered that the burning sensation imparted by essential oil containing mouth rinses such as LISTERINE® is principally attributable to the eucalyptol, rather than the thymol.
Accordingly, it is an object of the invention to provide a mouth rinse composition containing eucalyptol, wherein the harsh burn taste ordinarily imparted by the eucalyptol is masked.
It is a further object of the invention to provide an oral hygiene composition containing both eucalyptol and zinc, wherein both the burn taste of the eucalyptol and the astringency of the zinc are masked.
It is another object of the invention to provide an oral hygiene composition containing both eucalyptol and zinc, wherein the composition includes a component which coats and blocks the taste receptors in the mouth so as to eliminate or reduce the burn taste and astringency of the eucalyptol and the zinc.
These and other objects of the invention which will become apparent from the following detailed description are achieved by providing an oral hygiene composition containing eucalyptol and a zinc salt, wherein the harsh taste or burn sensation ordinarily imparted by the eucalyptol and the astringency ordinarily caused by the zinc salt are abated or eliminated by effective amounts in the composition of a taste receptor blocker, preferably in combination with a three component flavor system containing at least one spice, at least one sweetener and at least one fruity note. The taste receptor blocker is preferably a hydrogenated, ethoxylated glycerol ester which has the mouth feet characteristic of a fat but which has a much higher degree of solubility and hence improved clarity (i.e., reduced cloudiness) for the composition. Although effective amounts of the taste receptor blocker and the flavor component may vary depending upon the concentrations of eucalyptol and zinc salt in the composition, generally 0.5 to 5.0% by wt. taste receptor blocker and 0.05 to 0.25% by wt. flavor component are effective.
DETAILED DESCRIPTION OF THE INVENTION
It was surprising to discover that the eucalyptol, rather than the thymol which is also typically included in mouthwash compositions for its antimicrobial properties, is primarily responsible for the burning sensation in the mouth when used.
In accordance with the invention, an oral hygiene composition, such as a mouthwash or a dentrifice, containing eucalyptol, which is effective for its antimicrobial properties but which ordinarily imparts a burning sensation to the mouth of the user, is treated with an effective amount of one or more taste receptor blockers so as to reduce or eliminate the burning sensation. The function of the taste receptor blocker is to coat the taste receptors in the mouth and thereby impede or block direct contact with the eucalyptol contained in the oral hygiene composition. A particularly effective class of compounds which can function as taste receptor blockers for the eucalyptol are hydrogenated, ethoxylated glycerol esters. These types of compounds are commercially available and may be formed in a well-known manner, namely by the ethoxylation of glycerol. The ethoxylation may be accomplished by reacting the glycerol with ethylene oxide such that hydrogen bonding to the oxygen makes the polyethylene end of the molecule more soluble. As the ethoxylation number decreases, the fat character of the molecule and hence its efficacy in coating and blocking the taste receptors increases, but the solubility usually decreases thereby decreasing clarity. If the fat characteristics of the compound are too great, solubility in the mouth rinse is adversely affected which results in an undesirable cloudiness for the product. Good solubility is essential for product clarity. Accordingly, the taste receptor blocker should be selected so as to strike the proper balance between coating efficacy on the one hand and clarity on the other.
As discussed above, the hydrogenated ethoxylated glycerol esters are prepared by, hydrogenating castor oil and treating the resulting product with from about 10 to 200) moles of ethylene glycol. The ethoxylated compounds are designated as PEG (numeral) hydrogenated castor oil in accordance with the dictionary of the Cosmetics, Toiletries and Fragrance Association, 3
rd
Ed. wherein the numeral following PEG indicates the degree of ethoxylation, i.e. the number of moles of ethylene oxide added. Ethoxylation numbers in the range of from 35 to 60 have been found to provide the best results in terms of good solubility and good clarity (.e., minimal or no cloudiness). One commercially available compound which works particularly well is sold by the BASF Company under the trade name CREMOPHOR®. This compound is a hydrogenated ethoxylated castor oil. It has been found that CREMOPHOR 35 to CREMOPHOR 60 work particularly well.
The amount of taste receptor blockers incorporated in the composition will depend upon the amount of e
Stier Roger E.
Zanone John
Kenyon & Kenyon
Noville Inc.
Rose Shep K.
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