Flavour Blend For Masla_n~ Unpleasant Taste Of Zinc Co founds BACKGROUND OF THE INVENTION
1. Field of Invention. This invention relates to a flavouring method and flavour composition for masking flavour and taste of compositions for oral absorption and administration by humans which contain zinc compounds.
2. General back rg ound. The value of the element zinc is well-established.
Zinc has a vital role in a number of pharmaceutical formulations. Zinc deficiency is an important feature of many cases of sickle cell anaemia characterised by growth retardation and hypogonadism, and zinc appears to have an antisickling effect. Zinc has also been shown to be beneficial in the relief of acute inflammatory conditions associated with rheumatoid arthritis. Use of zinc gluconate and zinc acetate has been described as a method for reducing duration of common cold symptoms. Zinc oxides are used in a number of dental products such as dentifrices, denture adhesives, dental fillings, dental cements, and dental impression materials. Zinc salts are generally reported to enhance activity of triclosan and cationic anti-microbials in dentifrices and mouthwashes. Zinc chloride has been recognised as possessing anti-odour properties in oral health care products. Zinc citrates are useful in reducing dental calculus formation.
In recent years, formulations for oral administration and /or absorption such as tablets, powders, lozenges, syrups, sprays, dentifrices, mouthwashes, etc. have been formulated containing a zinc component. One of the major drawbacks of the incorporation of zinc compounds into various orally absorbed or administered products has been the characteristic bitterness of zinc that is experienced as soon as the zinc compound is released and proceeds to break down in the mouth. A variety of formulations and methods have been prepared and attempted to lessen or mask entirely the bitter taste and aftertaste of zinc compounds.
US Pat. Nos. 4,684,528 and 4,758,439 disclose the formulation of zinc compounds with glycine and certain other amino acids to reduce the unpalatable and undesirable aftertaste of prior zinc formulations. US Patent No. 5,095,035 teaches masking CA 02350450 2001-05-10..
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compositions which contain zinc acetate with the addition of extramoIar citric acid. US
Patent No. 5,002,970 discloses that ionisable zinc compounds can be masked with anethole to eliminate or reduce the taste and after taste of zinc. US Patent No.
5,766,622 teaches the use of phosphorylated amino acid in oral compositions to inhibit bitter and/or metallic taste from a pharmaceutical active component. US Patent No.
5,817,295 discloses a tripartite blend of peppermint oils that provides for a pleasant tasting mouthwash and masking the bitter taste of essential oils used for antimicrobial efficacy in the mouthwash.
There is still a need for a new way to eliminate the objectionable taste and after taste of zinc compounds using new technologies.
SUMMARY OF THE IIWENTION
The present invention relates to an orally administered formulation comprising about 0.1 to 25 wt. % of an ionisable zinc compound having an undesirable taste, and a synergistic flavouring combination of at least a flavouring oil and lauryl alcohol in an amount effective to mask the undesirable taste of said ionisable zinc compound.
The invention also provides a method for improving the taste of an orally administered formulation containing about 0.1 to 25 wt. % of an ionisable zinc compound with undesirable taste, by mixing into said formulation a synergistic flavouring combination of at least a flavouring oil and lauryl alcohol in an amount effective to mask the undesirable taste of said ionisable zinc.
The invention further provides a formulation consisting essentially of about 99.5 wt. % of at least a flavouring oil and about 0.5 to 20 wt. % lauryl alcohol, wherein said formulation when uniformly mixed into an orally administered formulation containing about 0.1 to 25 wt. % of an ionisable zinc compound with undesirable taste, masks the undesirable taste of said ionisable zinc compound.
DESCRIPTION OF THE INVENTION
The present invention provides an orally administered formulation containing an ionisable zinc compound with undesirable taste, but without the unpleasant metallic taste of zinc. The formulation can be in the form of foods, pharmaceuticals, toiletries, Printed~08-09-2000 CA 02350450 2001 05 10 j ~
'31 082000 PCT/GB:99/03779 DESG ~ ~<T
2a etc. The formulation contains an ionisable zinc compound and a carrier medium making up the balance.
Zinc Compounds. The orally administered formulations may contain one or more ionisable zinc compounds depending on the application. Zinc compounds include both inorganic and organic zinc salts and, in particular, salts such as the halides, nitrates, sulfates, chromates, silicates, and compounds comprising complexes of these materials constituting the inorganic salts contemplated herein. Organic salts of zinc include but not limited zinc pt~~D St4CET
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gluconate, zinc formate, zinc succinate, zinc aspartate and the like.
Particular zinc halides include zinc chloride, zinc bromide, zinc fluoride, and mixtures.
In teens of specific applications, typical zinc compounds used in dental formulations include such materials as zinc oxide for use in inhibiting bacterial attack in dentifrices. Zinc oxide is also used as a binding materials in denture adhesives. Zinc chloride and zinc citrate are used as anti-odour ingredients in dental formulations. Zinc acetate and hydroxide is used for their anti-plaque properties. Zinc citrate, polyphosphates such as disodium ethane-1-hydroxy-1, 1-diphosphonate (EHDP), pyrophosphate, tetrametaphosphate, metaphosphate and orthophosphate salts of zinc for tartar removal effects in dentifrices. Zinc glycerophosphate, zinc phenolsulfonate, zinc fluorosilicate, zinc fluorozirconate are known for their astringent and deodorant capabilities. Zinc citrate is preferred for dental formulations. Zinc acetate and zinc gluconate are favoured in compositions for treating common colds.
In general, the concentration of zinc compounds in orally administered formulations varies from about 0.1 to 15 wt. %. The concentration can range up to as much as 25% depending on the particular formulation in which the zinc compound is incorporated. A more preferred amount is about 0.2 to 2 wt. %. A most preferred amount is from about 0.5 to 2 vvt. %.
Flavourin,~ / maskin components: The taste masking / flavouring combination of the present invention is made up of a mixture of flavouring oils and lauryl alcohol.
For the purpose of this invention, flavouring oils used herein refer to both entire essential oils and the aroma chemicals making up the essential oils. Essential oils are predominately volatile materials from botanical sources. The most widely used process for the isolation of essential oils is steam distillation of plant matter, although dry distillation and solvent extraction are also used. Essential oils are generally recognised as safe compositions that can be included in ingested materials. Aroma chemicals refer to chemicals which may be synthetic or natural, derived from essential oils, i.e., derived from plants by distillation, expression, or extraction, and which usually carry the flavour of the plant from which they are derived.
Although the invention is not limited to the specific essential oils listed individually in this specification, a number of important essential oils include spearmint oil; peppermint oil; wintergreen oil; lavender oil; sassafras oil; ginger oil; clove oil; sage oil; basil oil;
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oil; laurel oil; mayonara oil; cinnamon oil; camomile oil; thyme oil; citrus oils such as lemon oil, orange oil, grapefruit oil, tangerine oil; oil of anise; camphor oil; and the like.
Aroma chemicals include but not limited to anethole, carvone, cintronellal, camphor, linalool, menthol, menthone, thymol, and the like. .
It has been found that in an orally administered formulation of the claimed invention, the additional presence of lauryl alcohol in combination with a mixture of flavouring oils as a flavouring composition, enhances the organoleptic properties, imparts freshness in the mouth and masks the unpleasant taste and aftertaste of the zinc compound in the formulation. The flavouring oils appear to be operating in synergistic combination, perhaps with the lauryl alcohol ar perhaps because of the ability of various components of the flavouring oils themselves to inhibit different biological pathways associated with bioavailability.
The individual flavouring oils can be mixed and matched as desired to provide the intended flavour in the orally administered fomnulation. The concentrations of the individual components can therefore vary quite widely. It is preferred, nevertheless, that the flavouring oils in total will be about 80 - 99.5 wt. % of the synergistic taste masking / flavouring combination, and most preferred about 95 - 99%. The lauryl alcohol makes up the rest of the masking I flavouring combination.
In general, the synergistic taste masking / flavouring combination is present in an amount of about 0.1 to 5 wt. % of the orally administered formulation. A
preferred amount is about 0.1-3% wt. %. A most preferred amount is from about 0.1 to 2 wt. %.
Carriers & Other Ingredients: The carriers vary according to the applications.
In toothpastes it is desirable to employ thickening agents such as hydroxyethylcellulose and water-soluble salts of cellulose ethers, including sodium carboxymethyl cellulose and sodium carboxymethylhydroxyethyl cellulose; or natural gums, including gum karaya, gum arabic, and gum tragacanth. Also, colloidal magnesium aluminium silicate or finely divided silica can be used as part of the thickening agent to improve the texture of the product. Thickening agents are used at levels of from 0.1 % to 5.0% of the toothpaste composition. It is also desirable to include a humectant material in toothpastes. Suitable materials for this purpose include glycerine, sorbitol, and other edible polyhydric alcohols or mixtures thereof. These materials can comprise from about 1% to about SO% of the toothpaste composition. Dentifrices normally also contain sweetening agents. Suitable sweetening agents for use in dentifrices include for example saccharin, dextrose and levulose. The sweetening agents are i~~~'ii~t~ Sf~~
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used at levels of from about 0.05% to about 2%. In addition to the aforementioned typical components of a toothpaste, water usually comprises the balance of the toothpaste, and is usually present at levels up to about 50%.
Mouth rinses generally comprise a water/ethyl alcohol solution and optionally other ingredients such as sweeteners, and humectants such as those mentioned above for dentifrices. The alcohols provide an antibacterial effect and help the solubility of the flavouring oils. Optionally, mouth rinses also contain sudsing agents.
Humectants such as glycerine and sorbitol give a moist and sweet feel in the mouth and are desirably also present. While these materials are not always essential, they are useful to help solubilise and enhance the flavouring oils, and aid in making the product sweet, smoother and imparting body. Antibacterial agents are sometimes incorporated into mouthwashes or dentifrices at levels from about 0.01 % to about 2.0%. Generally, mouth rinses suitable for use as carriers herein contain: 5% to 40% ethyl alcohol; 0% to 20%, preferably 5%
to 20%, glycerine or other humectant; 0% to 12%, preferably 0.1 % to 12%, sudsing agent, 0% to 0.5%, preferably 0.05% to 0.5%, sweetening agent such as saccharin; and 0% to 0.3%, preferably 0.05% to 2% of the flavouring I masking combination of the present invention; and the balance, water with colorants or dyes if desired.
Chewing gum suitable for use as a carrier herein comprises a gum base and flavouring materials such as those mentioned above for dentifrices. The flavouring materials are present at a level of 0.01% to about 2.0% of the final chewing gum composition. The gum base is a chewable plastic gum material such as natural rubber, chicle, polyvinyl acetate, ester gum, coumarone resin, and paraffin wax. The gum base is typically made from a mixture of two or more plastic gum materials to achieve a preferred degree of plasticity for chewing. Optionally, corn syrup is added as a softener and binder for the chewing gum and sugar is optionally added as a sweetener and adding nuance to the flavour. A typical chewing gum suitable as a carrier herein comprises 15%
to 30% gum base, 15% to 20% corn syrup, 50% to 65% sugar, 1% of zinc gluconate trihydrate, and 0.05% to 1.5% of the flavouring / masking combination of the invention.
Lozenges suitable as carriers herein comprise a hard sugar candy base and one or more flavouring oils. Optionally, lozenges can contain various other materials. A
typical lozenge suitable as a carrier in this invention is a hard candy comprised of a hard candy base containing 0.05% to 1.5 wt. % of the flavouring l masking combination and about 1 wt. % of ~.~~~~",~D STET
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flES!C ~;r zinc acetate dihydrate. The hard candy base is a solidified solution of amorphous sugar which is generally formed from a sugar solution which has been cooked at high temperature so as to remove nearly all of the moisture. The taste masking /
flavouring combination is added before the moisture is removed.
The orally administered formulations of the present invention can also optionally contain additional therapeutic materials including for example, water-soluble fluoride such as sodium fluoride and stannous fluoride.
Preparations: The orally administered formulations of the present invention without the metallic zinc taste can be prepared by any convenient method. The individual components of the synergistic masking l flavouring composition can be added separately as separate components to the orally administered formulations, but it is generally preferred to prepare the masking / flavouring composition separately and thereafter combine it with the orally administered compositions.
The orally administered formulations of the present invention can be in solid forms such as tablets, lozenges and powders; chewable forms such as chewing gums and soft candies; paste and gel forms such as dentifrices; liquids such as syrups, mouthwashes, and sprays. Flavoured lozenges with zinc compounds can be prepared by mixing the masking components of the present invention with the carriers and other ingredients, then by direct compression of the ingredients.
When the compositions are applied to or in contact with oral and oral pharyngeal membranes of a human, they are palatable and without undesirable taste or unpleasant metallic taste of zinc compounds. The flavours produced are truer, smoother, and better in taste than formulations without the masking/flavouring components of the present invention. In order to further illustrate the present invention, examples are set forth below. All parts and percentages are by weight and all temperatures in degrees in centigrade unless otherwise indicated.
Various flavouring formulations compositions were prepared by mixing the components (in wt. %) set forth in Table 1 that follows:
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::.,z~. _.. ,..~_...~... ..~, . , ~.v.i.LL -._,.....a...v 3.,.vv,i.m Irav~.v .~~~3 ... .yf Ingredient Example CompareCompare Example 1-Menthol 31.3 13.9 9 35.4 Peppermint 24.3 27.8 54 25.3 Oil 1-Carvone 21.5 17.6 - 29.3 Spearmint I 8.0 32.4 17 5 Oil SOI50 Anethole 3.5 8.3 _ 4 Lauryl Alcohol,1.4 - _ 1 Optacool (T'Ivl7- - 20 -The flavour formulations were combined into a dentifrice formulation containing the following components, shown in Table 2 below:
Ingredients Parts By Weight Sorbitol Solution 27 Glycerine 10 Amorphous Silica 10 Cocamidopropyl Betaine4 KCI 3.75 Zinc Citrate Colloidal Silica 1.7 Sodium Carboxymethyl1.6 Cellulose Flavour Blend 1 Titanium Dioxide 0,5 Carboxymethyl Cellulose0.4 Sodium Saccharine 0.4 Sodium Fluoride 0.3 Trisodium Phosphate 0.2 ~ Water Qs to 100 In blind taste tests, it is found that the dentifrice compositions containing the masking / flavouring compositions in the Examples exhibit "good tasting"
properties and without any trace of the unpleasant metallic taste of zinc compounds.
Various changes and modifications can be made in the products of the present invention without departing from the spirit and scope thereof. The various embodiments which were disclosed herein were for the purpose of further illustrating the invention but were not intended to limit it.
A~~~ii~D ~Ff Prlnted:08-09-2000