WO1998037859A1

WO1998037859A1 - An oral composition suitable for use in oral hygiene and dental care

Info

Publication number: WO1998037859A1
Application number: PCT/DK1998/000078
Authority: WO
Inventors: Carsten Andersen
Original assignee: Fertin A/S
Priority date: 1997-02-28
Filing date: 1998-02-27
Publication date: 1998-09-03
Also published as: AU6290698A

Abstract

An oral composition comprises at least one physiologically acceptable, easily soluble zinc salt of an inorganic or organic acid and at least one taste-masking salt selected among sodium chloride, ammonium chloride and physiologically acceptable alkali metal, alkaline earth metal and/or ammonium carbonates. The composition is suitable for use in dental care and oral hygiene including prevention and control of mouth odour, plaque and/or calculus. The oral composition is advantageously in form of lozenges, pastilles or chewing gum. The use of the taste-masking salt in the zinc-containing oral composition ensures an efficient reduction of the astringent taste of the zinc ions.

Description

Title: An oral composition suitable for use in oral hygiene and dental care

Technical Field

The present invention relates to an oral composition suitable for use in oral hygiene and dental care including prevention and control of mouth odour, calculus and/or plaque. The invention relates furthermore to the use of at least one taste-masking salt selected among sodium chloride, ammonium chloride and physiologically acceptable alkali metal, alkaline earth metal and ammonium carbonates in a zinc-containing oral composition for reducing the astringent taste of zinc.

Background Art

It is generally recognized that zinc has a useful effect in oral hygiene and dental care as it is effective against caries, calculus, periodontal disease and plaque, as well as that it has a useful prophylactic and controlling effect against mouth odour.

In addition, zinc is used as a food supplement, and recent research indicates that zinc has a beneficial effect against cold as well.

Thus the literature discloses several zinc-containing oral compositions, especially toothpastes and mouthwashes, to be used for oral hygiene and dental care.

Zinc is, however, encumbered with the draw-back that it has a highly astringent effect which causes an unpleasant taste sensation and leaves an unpleasant feeling in the mouth.

Various attempts have been made at solving this problem. US-PS No. 4, 1 38,477 (Colgate) discloses an oral composition to prevent and control mouth odour, calculus, plaque, caries and periodontal disease, said composition comprising a combination of a zinc compound and an anionic polymer. The use of said combination is indicated to reduce the astringent taste of the zinc ions which results in an improved taste.

The combination of the zinc compound and the anionic polymer is, however, difficult to prepare, and it is generally not approved for use in foodstuffs.

The DK-PS Nos. 1 67,336 and 1 67,337 (Colgate) disclose oral composi- tions against mouth odour and calculus, said compositions comprising a combination of a relatively easily-soluble zinc compound and an ionon keton terpene derivative. According to the patent specifications the use of such a combination results in a prolonged effective period and a synergist- ic effect against mouth odour, whereby it is possible to use a reduced amount of the zinc-containing compound for achieving a useful effect. Ionon keton terpene derivatives may be allergenic, and they provide the oral composition with a specific taste which limits the freedom of choice of the taste.

US-PS No. 4,289,755 (Richardson-Vicks Inc.) discloses a mouthwash composition inter alia for preventing mouth odour, said mouthwash composition comprising a combination of zinc citrate, sodium fluoride, citric acid and an alkali compound for neutralising the pH value to 6.0 to 7.2. The mouthwash is indicated to have a reduced astringent effect and to be compatible with fluoride ions. The preparation of the mouthwash requires a careful measuring and control of the individual ingredients, and the achieved reduction of the astringent taste of zinc has only been demonstrated in connection with the presence of citric acid and sodium fluoride within the indicated pH range. US-PS No. 4,325,939 (Richardson-Vicks Inc.) discloses a composition with anti-odour properties, especially a mouthwash, said composition comprising an alkali metal or ammonium salt of zinc citrate. This complex or double salt results from a separate step prior to the preparation of the mouthwash, and accordingly the preparation thereof is rather complicated. The composition is indicated to have a reduced astringent effect without loss of anti-odour properties.

WO95/34274 discloses an oral hygiene composition comprising an unpalatable species as well as a palatability-improving amount of alkali metal bicarbonate. The ill-tasting ingredient can for instance be zinc ions. The disclosed oral hygiene composition possesses, however, only a limited taste-masking effect.

Brief Description of the Invention

The object of the present invention is to provide an oral composition, which in a simple manner allows reduction of the astringent effect of zinc while maintaining its useful effects including an efficient effect against mouth odour, calculus and/or plaque, and while providing a palatable product.

The oral composition according to the invention is characterised by com- prising i) at least one physiologically acceptable, easily soluble zinc salt of an inorganic or organic acid; and ii) at least one taste-masking salt selected among sodium chloride, ammonium chloride and physiologically acceptable alkali metal, alkaline earth metal and/or ammonium carbonates.

The invention relates also to the use of at least one taste-masking salt selected among sodium chloride, ammonium chloride and physiologically acceptable alkali metal, alkaline earth metal and/or ammonium carbonates in a zinc-containing oral composition to reduce the astringent taste of zinc. The oral composition according to the invention is suitable for use in oral hygiene and dental care, and accordingly, the invention relates also to the use of at least one physiologically acceptable, easily soluble zinc salt of an inorganic or organic acid and at least one taste-masking salt selected among sodium chloride, ammonium chloride and physiologically acceptable alkali metal, alkaline earth metal and/or ammonium carbonates for the preparation of an oral composition to be used in oral hygiene and dental care, especially for the prevention and control of mouth odour, calculus and/or plaque. It should, however, be understood that the oral composition according to the invention is not limited to the use in oral hygiene and dental care, and thus it may be used for instance as a food supplement and against cold.

The extent of applicability of the invention appears from the following detailed description. It should, however, be understood that the detailed description and the specific examples are merely included to illustrate the preferred embodiments, and that various alterations and modifications within the scope of protection will be obvious to persons skilled in the art on the basis of the detailed description.

Detailed Description of the Invention

The present combination of salts renders it possible in a simple manner to achieve a substantial reduction of the astringent effect of zinc while maintaining its useful effects including an efficient effect of prevention and control of mouth odour, calculus and/or plaque without involving the more complicated solutions, cf. the captioned US-PS Nos. 4,289,755 and 4,325,939. Further a more pronounced taste-masking effect compared to that of WO 95/34274 is achieved. It is indeed surprising that such a combination results in a reduction of the astringent effect of zinc because many of the taste-masking salts used have per se a relatively pronounced and more or less unpleasant taste.

The present invention is further advantageous in the salts used being easily available and inexpensive raw materials, and many of these salts are already included in the lists of EU concerning substances approved for use in foodstuffs with the result that they may be used without problems in for instance chewing gum, pastilles and lozenges.

As easily soluble zinc salt it is in principle possible to use any physiologically acceptable, easily soluble zinc salt of an inorganic or organic acid, said salt being able to release zinc ions and being approved for the intended use, such as in foodstuffs, cosmetics or pharmaceutical products. Non-limiting examples are for instance zinc citrate, zinc sulphate, zinc lactate, zinc chloride, zinc acetate as well as mixtures thereof. Among these salts zinc acetate is preferred.

The zinc salt used must be easily soluble such that upon administration of the oral composition according to the invention a release is ensured in the oral cavity of an amount of zinc ions efficient for the purpose aimed at within a suitable period of time.

An efficient amount of released zinc ions for prevention and control of mouth odour is assumed to be an amount producing a concentration in saliva of from 0.00002 to 0.1 % by weight, preferably 0.0001 to 0.006% by weight. An easily soluble zinc salt is in the present invention a zinc salt with a solubility of at least 0.01 g/ml of water at room temperature, such as at least 0.1 g/ml.

Depending on the administration form used and the release profile desired the zinc salt is advantageously selected on the basis of inter alia its solubility. Advantageously, the zinc salt is present in the oral composition in an amount of from 0.001 to 1 .25% by weight. The amount used depends on the administration form and the intended use and is adapted such that an amount of zinc ions efficient for the intended use is released.

When the oral composition is a chewing gum preparation for prevention and control of mouth odour, said composition comprises thus advantageously the zinc salt in an amount of from 0.001 to 1 .25% by weight, more preferred 0.004 to 0.20% by weight, such as 0.01 to 0.08% by weight calculated as zinc ion and based on the weight of the core of the chewing gum, which corresponds to an amount of from 0.008 mg to 1 0 mg, 0.032 mg to 1 .6 mg and 0.08 mg to 0.64 mg, respectively, of zinc ion per piece in a chewing gum preparation with a core weight of 800 mg.

A chewing gum preparation for prevention and control of plaque with a core weight of 800 mg comprises advantageously an amount of from ap- proximately 1 to 10 mg of zinc ion per piece.

When the chewing gum preparation is to be used for prevention and control of calculus, an efficient amount of the zinc salt is in the range of from approximately 0.02 to 3 mg of zinc ion per piece for a preparation with a core weight of 800 mg.

As taste-masking salt is used at least one salt selected among sodium chloride, ammonium chloride and physiologically acceptable alkali metal, alkaline earth metal and/or ammonium carbonates.

The alkali metal is in particular sodium or potassium, whereas the alkaline earth metal advantageously is calcium or magnesium.

Particularly preferred taste-masking salts are sodium, potassium and magnesium carbonates, sodium chloride, ammonium chloride as well as mix- tures thereof.

The taste-masking salt is advantageously used in the oral composition in an amount of from 0.05 to 6.25% by weight, more preferred from 0.25 to 3.50% by weight, such as from 0.50 to 2.50% by weight.

The amount used of taste-masking salt for masking the taste of zinc can in each case be determined by a person skilled in the art and depends on the particular zinc salt in question and the selected administration form.

In other words the ratio of the zinc salt used to the taste-masking salt must be adjusted in each case in such a manner that the most efficient masking of the taste of zinc is achieved while maintaining the desired useful effect of the zinc ions. Suitable weight ratios of the zinc salt to the taste-masking salt can be determined by persons skilled in the art by way of experiments and are typically in the range of from 1 : 1 to 1 : 1 00, such as from 1 :3 to 1 :40, for instance from 1 : 1 0 to 1 :35, where the amount of zinc salt is calculated as zinc ion.

The oral composition can exist both in solid and in liquid form, such as for instance in form of mouthwashes, toothpaste, chewing tablets, lozenges, resoribletts, pastilles, effervescent tablets to be dissolved in the mouth without the administration of liquid, drops, sweets and chewing gum. In addition, the oral composition can be in form of a mouthspray.

The oral composition exists advantageously in solid dosage form, such as lozenges, pastilles and chewing gum, and a unit dose typically weighs between 0.5 and 7.5 g. The following table indicate preferred intervals of various types of products:

Chewing gum pieces without coating 750 to 2000 mg

Chewing gum tablets with coating 900 to 3000 mg Chewing gum in form of sticks 1 .5 to 5.0 g

Bubble gum 1 .0 to 7.5 g

Pressed chewing tablets and lozenges 0.5 to 3.0 g

Moulded lozenges (pastilles) 0.5 to 3.0 g

The oral composition can furthermore be formulated as a composition with a controlled release of the zinc salt, when a shorter or prolonged release is desired of the zinc salt compared to the effect achieved without the addition of components increasing or delaying the release. When formulating such long-acting preparations with a controlled release of the zinc salt it is often an advantage to ensure a controlled release of the taste-masking salt in such a manner that the most efficient masking of the zinc taste is obtained. When formulating preparations with a prolonged release of the salts, it is often advantageous to incorporate relatively high amounts thereof. Such preparations with a controlled release are conventionally prepared in the manner well-known inter alia within the pharmaceutical industry.

Moreover, the oral composition according to the invention may, if desired, include any other active ingredients, such as anti-caries agents, anti-calculus agents, anti-plaque agents, anti-periodontal agents, antifungal agents, anti-smoking agents, anti-cold agents, agents against gingivitis etc.

According to a preferred embodiment, the oral composition is a chewing gum preparation.

Such a chewing gum preparation preferably comprises the easily soluble zinc salt in an amount of from 0.008 to 1 0 mg, calculated as zinc ion, per piece. The weight of a piece of chewing gum is usually in the range of 0.8 to 4 g, but the weight per piece can be adjusted to the amount of zinc salt used. Thus, it is often advantageous to use a high weight per piece of chewing gum in connection with a high concentration of the zinc salt.

According to a preferred embodiment, the chewing gum preparation comprises the taste-masking salt in an amount of from 0.4 to 50 mg, more preferred from 2 to 30 mg, such as from 1 0 to 20 mg per piece. The amount of taste-masking salt used must be adapted to the amount of zinc salt used in such a manner that an efficient masking of the astringent taste of the zinc ions is obtained.

When the oral composition according to the invention is a chewing gum, it can be any known type of chewing gum, such as chewing gum pieces optionally coated, as well as sticks or chewing gum provided with an arbitrary desired shape in response to the intended use. The chewing gum preparation can be of any quality including the bubble gum quality. No limitations as to the chewing gum bases used in a chewing gum preparation according to the invention exist. Conventional chewing gum bases available for instance from Dansk Tyggegummi Fabrik A/S, L.A. Dreyfus or Cafosa Gum S/A, are usually suitable, but specially made formulations can also be used. The formulation depends on the desired type of chewing gum or the desired type of structure. Suitable raw materials for gum bases include the substances according to the U.S. Chewing Gum Base Regula- tions - Code of Federal Regulations, Title 21 , Section 1 72,61 5 and in accordance with other national and international lists (or positive lists) and include elastomers, resins, waxes, fats, emulsifiers, fillers and antioxi- dants.

The gum base usually comprises from 1 5 to 90% by weight, preferably from 30 to 40% by weight of the final product.

The remaining adjuvants in the chewing gum preparation are completely conventional and usually comprise from 1 0 to 85% by weight of the final product. Examples thereof are sweeteners, softeners, dyes and flavourants of the type and in the amounts conventionally used for chewing gum.

Examples of suitable flavourants are peppermint, wintergreen, eucalyptus, spearmint, menthol, fruit flavours and besides all flavours suitable for confectionary and toothpaste, including mixtures of flavours. The flavourants are used in accordance with the EEC Council Directive (88/388/EEC) and the pharmacopoeia and food monographs in force at the time in question.

It is recommended to use sweeteners not having a deleterious effect on the teeth as sweetener in the chewing gum preparations according to the invention. Examples thereof are sorbitol, xylitol, maltitol, mannitol, isomalt, glycerol, aspartame, acesulphame K, saccharine and salts thereof, cyclamate and salts thereof, neohesperidine dihydrochalcone, glycyrrhizinic acid and salts thereof, thaumantine and sucralose as well as mixtures thereof or mixtures thereof with other suitable sweeteners. These sweeteners are used in accordance with the national and international provisions in force at the time in question, cf. for instance pharmacopoeia and food monographs.

The chewing gum preparation preferably comprises powdered sorbitol and/or xylitol in an amount of from 40 to 80% by weight, such as from 45 to 70% by weight.

Sorbitol syrup, maltitol syrup and/or glycerol can advantageously be used in an amount of from 0 to 30% by weight, such as from 0.5 to 1 5% by weight.

The oral composition according to the invention can also advantageously be in form of lozenges. Apart from the fact that the lozenges according to the invention must comprises a lubricant and not chewing gum base, the adjuvants in the lozenges are substantially the same as the ones disclosed above in connection with the chewing gum preparations.

The lozenges can, of course, also comprises additional additives conventional for lozenges.

The invention is explained in detail in the following examples.

Example 1

Based on the following recipe, chewing gum in form of cores for coating was prepared in a completely conventional manner. The cores have a weight per piece of 800 mg.

Recipe 1

Gum base 38% by weight

Sorbitol powder 47.5% by weight Maltitol syrup 70% 6% by weight

Xylitol 5% by weight

Flavourants 2% by weight

Zinc acetate 0.25% by weight

Ammonium chloride 1 .25% by weight

The recipes indicated in the following Table I were prepared in the same manner and based on the same basic recipe, the amount of sorbitol powder being adjusted to the amounts of salts indicated in the Table in such a manner that the total amount was 100% by weight. Recipe No. C1 was prepared without a content of taste-masking salt, i.e. component ii) and serves exclusively as comparison example. Recipe No. C2 was prepared in a similar way as recipe No. 1 , but with the known taste-masking salt sodium bicarbonate.

Table I

ω

Comparison Example

Example 2

The present example illustrates the preparation of chewing tablets and lozenges according to the invention. The ingredients indicated below were mixed and tabletted in a conventional tabletting machine. Each tablet has a weight of 1 .0 g and comprises 2 mg of zinc acetate and 1 0 mg of sodium chloride.

Recipe No. 5

Sorbitol powder 97.3% by weight Magnesium stearate 1 .0% by weight Peppermint taste 0.5% by weight Zinc acetate 0.2% by weight Sodium chloride 1 .0% by weight

Example 3

Based on the following recipe pastilles were prepared.

Recipe No. 6

Gum arabic 35.0% by weight Sorbitol powder 63.5% by weight Peppermint taste 0.3% by weight Zinc acetate 0.2% by weight Sodium chloride 1 .0% by weight

The gum arabic was dissolved in water and mixed with the remaining ingredients. Then pastilles were pastilled in a conventional manner. Each pastille has a weight of 1 .0 g and comprises 2 mg of zinc acetate and 10 mg of sodium chloride. Example 4

The present example illustrates the preparation of chewing gum in form of cores for coating. The chewing gum cores were prepared in a completely conventional manner and cut into pieces of 900 mg, each piece compris- ing 1 .2 mg of zinc sulphate monohydrate (corresponding to 0.44 mg zinc ion) and 1 0 mg of sodium chloride.

Recipe No. 7

Gum base 37.0% by weight

Sorbitol powder 54.1 7% by weight Maltitol syrup 70% 5.0% by weight

Lecithin 0.2% by weight

Aspartame 0.2% by weight

Acesulphame K 0.2% by weight

Flavourants 1 .7% by weight Zinc sulphate monohydrate 0.1 3% by weight

Sodium chloride 1 .1 % by weight

Example 5

The present example illustrates a test for examining the masking of the zinc taste in the chewing gum cores prepared in Example 1 .

The chewing gum cores were tested by a trained test panel of 2 to 3 persons evaluating the chewing gum cores according to a scale from 0 to 3, 0 indicating the poorest observed masking of zinc during the chewing of the comparison recipe and 3 indicating an effect corresponding to "no zinc taste". The evaluation was performed while chewing for at least 3 minutes. The taste sensation of the zinc salt at chewing of non-coated chewing gum cores usually proceeds such that during the first chewing phase lasting from approximately 0 to 1 .5 minute zinc is not released in an amount sufficient for being tasted. Then follows a phase lasting from approximately 1 .5 to 3 minutes wherein the zinc taste is increased and where the added taste-masking salt simultaneously exerts its maximum effect. During the following phase the release of both the zinc salt and the taste-masking salt decreases, and the taste sensation decreases correspondingly.

The evaluation of the recipes involved the use of measuring values resulting from the phase in the chewing process where a maximum taste sensation applies. Thus the results are indicated as an average of the evaluations of the taste persons at the times 1 .5 minute, 2 minutes and 3 minutes.

The results appear from the following Table II.

Table II

Comparison Example

As shown in Table II, a good masking of the zinc taste is obtained by the compositions according to the invention.

The above invention having now been disclosed, it is obvious that it can be varied in many ways. Such variations are not to be considered a devia- tion from the scope of the invention, and all such modifications which are obvious to persons skilled in the art are also to be considered comprised by the scope of the appending claims.

Claims

1. An oral composition, c h a r a ct e r i s e d by comprising

i) at least one physiologically acceptable, easily soluble zinc salt of an inorganic or organic acid; and

ii) at least one taste-masking salt selected among sodium chloride, ammonium chloride and physiologically acceptable alkali metal, alkaline earth metal and/or ammonium carbonates.

2. An oral composition as claimed in claim 1, characterised by the easily soluble zinc salt being selected among zinc chloride, zinc sul- phate, zinc lactate, zinc acetate as well as mixtures thereof.

3. A oral composition as claimed in claim 2, c ha ra cte rised by the easily soluble zinc salt being zinc acetate.

4. An oral composition as claimed in any of the preceding claims, c h a r a c t e r i s e d by the taste-masking salt being selected among sodium, potassium and magnesium carbonates, sodium chloride, ammonium chloride as well as mixtures thereof.

5. An oral composition as claimed in any of the preceding claims, c h a r acte ri se d by comprising from 0.001 to 1.25% by weight of the easily soluble zinc salt, calculated as zinc ion, and from 0.05 to 6.25% by weight of the taste-masking salt.

6. An oral composition as claimed in any of the preceding claims, c h a racte rised by the weight ratio of i) the easily soluble zinc salt, calculated as zinc ion, to the ii) taste-masking salt being from 1:1 to 1 : 100, such as from 1 :3 to 1 :40.

7. An oral composition as claimed in any of the preceding claims, c h a r a c t e r i s e d by being present in form of chewing tablets, lozenges, pastilles, effervescent tablets or chewing gum.

8. An oral composition as claimed in claim 7, c h a r a ct e r i s e d by being a chewing gum preparation, and by comprising per piece the easily soluble zinc salt in an amount of from 0.008 mg to 10 mg, calculated as zinc ion.

9. An oral composition as claimed in claim 7 or 8, c h a ra cte r- is e d by comprising per piece the taste-masking salt in an amount of from 0.4 mg to 50 mg, such as 2 mg to 30 mg.

10. The use of at least one taste-masking salt selected among sodium chloride, ammonium chloride and physiologically acceptable alkali metal, alkaline earth metal and/or ammonium carbonates in a zinc-containing oral composition to reduce the astringent taste of zinc.

11. The use of at least one physiologically acceptable, easily soluble zinc salt of an inorganic or organic acid and at least one taste-masking salt selected among sodium chloride, ammonium chloride and physiologically acceptable alkali metal, alkaline earth metal and/or ammonium carbonates for the preparation of an oral composition for use in oral hygiene and dental care.

12. The use as claimed in claim 11 for the preparation of an oral composition for the prevention and control of mouth odour.

13. The use as claimed in claim 11 for the preparation of an oral compo- sition for the prevention and control of plaque and/or calculus.