WO2008145475A1

WO2008145475A1 - Oral care composition

Info

Publication number: WO2008145475A1
Application number: PCT/EP2008/055398
Authority: WO
Inventors: Irene Ingegneri
Original assignee: Unilever Plc; Unilever N.V.; Hindustan Unilever Limited
Priority date: 2007-05-31
Filing date: 2008-05-01
Publication date: 2008-12-04
Also published as: WO2008145475A8

Abstract

An oral care composition: a zinc salt, an anionic surfactant, an amphoteric surfactant, and a poloxamer.

Description

ORAL CARE COMPOSITION

The present invention relates to oral care compositions comprising zinc salts and having superior sensory benefits.

Oral care compositions comprising zinc are known in the art. EP-Al-O 740 932 (Unilever) discloses a gel type dentifrice comprising a zinc salt which is more water soluble than zinc citrate. US 5,470,561 (Klugkist) discloses an anti-plaque mouthwash comprising a zinc salt and triclosan. GB 2,052,978 (Unilever) discloses a toothpaste comprising zinc salts with glycine. US 5,632,972 (Williams) discloses a method for minimising damage to gingival and periodontal tissue by delivering a first component comprising zinc and a second component comprising a bicarbonate. US 4 325 939 (Shah) discloses an alkali metal or ammonium zinc citrate prepared for use in dental compositions and especially in mouthwash compositions. US 5,188,820 (Cummins et al) discloses oral compositions comprising a mixture of a stannous salt and a zinc salt such as zinc citrate.

Oral care compositions comprising surfactants, such anionic, non-ionic, or amphoteric surfactants are also known in the art. 02/26203 (Henkel, 2002) discloses dental cleaning agents comprising surfactants or tensides in the form of a combination of anionic tensides, betaine tensides, and ethoxylated fatty acid-polyol monoesters. WO 95/01173 (Unilever, 1995) and US 6,169,118 (Unilever, 2001) disclose amphoteric surfactants in toothpaste compositions. Also known in the art are oral care compositions comprising non-ionic polymers, such as poly (ethylene glycol) - poly (propylene glycol) block co-polymers, known as "poloxamers". Such compositions are described in US 6,187,295 (P&G, 2001) .

We have found that by carefully selecting particular components from amongst those mentioned above, it is possible to formulate oral care compositions comprising zinc salts that have superior sensory properties and other properties. In particular, we have found it possible to formulate toothpaste compositions that have superior texture, flavour, and reduced astringency without compromising sensory perceptions of foam quantity and foam quality.

In a first of aspect of the present invention, there is provided an oral care composition comprising a zinc salt, an anionic surfactant, an amphoteric surfactant, and a poloxamer.

In a second of aspect of the present invention, there is provided a method of cleaning the teeth comprising brushing with a composition according to the first aspect of the invention.

In a third of aspect of the present invention, there is provided the use of a poloxamer to improve the in use foam quantity and/or quality of an oral care composition also comprising a zinc salt, an anionic surfactant and an amphoteric surfactant. The sensory benefits given by compositions according to the invention are found both in use and after use. We have found that compositions according to the invention are perceived to have good texture in use and also good foam quantity and foam quality. In addition, compositions according to the invention give high flavour intensities both in use and after use and low astringency after use. It is believed that these benefits are related to the particular combination of surfactants and non-ionic polymer selected for use in the compositions of the invention.

The oral care compositions of the present invention may take any of the forms commonly used for such purpose; however, toothpastes are a particularly suitable form.

The zinc salt used in accordance with this invention may give benefits associated with its anti-microbial properties, such as reduced gingivitis, plaque, sensitivity, and/or bad breath.

A problem encountered with some prior art compositions comprising zinc salts has been a relatively high level of astringency. This problem, amongst others, is at least partially overcome by the compositions of the present invention.

The zinc salt used in accordance with the invention is typically soluble in water, meaning that it has a solubility in water of at least 0.1 g/1 at 25°C. Preferably, the zinc salt has a solubility in water at 25°C of at least 1 g/1 and more preferably at least 2 g/1. Particularly preferred zinc salts are zinc citrate, zinc sulphate, glycinate, and zinc chloride. Mixtures of zinc salts may also be employed. Zinc citrate is the most preferred zinc salt for use in the compositions of the invention.

The total amount of zinc salts is typically from 0.1 to 10%, in particular from 0.5 to 5%, and especially from 1 to 3% by weight of the total composition.

The anionic surfactant used in accordance with the invention is preferably an alkali metal alkyl sulphate, more preferably a sodium linear alkyl (Cio-Ciβ) sulphate, and most preferably sodium lauryl sulphate (SLS) . Mixtures of anionic surfactants may also be employed.

The total amount of anionic surfactant is preferably from 0.1 to 10%, more preferably from 0.2 to 5%, and especially from 0.5 to 2% by weight of the total composition.

The amphoteric surfactant used in accordance with the invention is preferably a betaine, more preferably an alkylamidopropyl betaine (wherein the alkyl group is a linear Cio~Ci8 chain) , and most preferably is cocoamidopropyl betaine (CAPB) . Mixtures of amphoteric surfactants may also be employed.

The total amount of amphoteric surfactant is preferably from 0.1 to 10%, more preferably from 0.2 to 5%, and especially from 0.5 to 2% by weight of the total composition. The poloxamer used in accordance with the invention is a difunctional block-polymer of poly (ethylene glycol) (PEG) and poly (propylene glycol) (PPG) . Such non-ionic polymers are sold under the tradename of Pluronics by BASF. Preferred polaxamers have a block of PPG surrounded by blocks of PEG, in accordance with this formula:

HO- (ECOa-(PO)b- (EO) _a-H

wherein EO = CH₂-CH₂-O; PO = CH₂-CH (CH3) -0; and a:b = from 1:2 to 5:1.

Preferred poloxamers of the above formula have a:b = from 1:1 to 3:1, especially when a = from 80 to 120 and b = from 40 to 70.

A most preferred poloxamer has the CTFA designation of Poloxamer 407. Mixtures of poloxamers may also be employed.

The total amount of poloxamer is preferably from 0.1 to 20%, more preferably from 0.5 to 10%, and especially from 1 to 3% by weight of the total composition.

The sensory benefits, in particular those of foam quality and quantity, delivered by the present invention may be sensitive to the relative amounts anionic surfactant, amphoteric surfactant, and poloxamer employed. Thus, it is preferred that the ratio of the sum of the total amounts of anionic and amphoteric surfactant to the total amount of poloxamer is from 1:5 to 5:1, more preferably from 1:2 to 2:1, and most preferably from 0.8:1.2 to 1.2:0.8 by weight.

A highly preferred additional component in compositions of the invention is an abrasive. In some compositions, the abrasive may contribute to the in use sensory properties. Suitable abrasives are particulate materials such as silica, alumina, calcium carbonate, dicalciumphosphate, calcium pyrophosphate, hydroxyapatite (HAP) , trimetaphosphate, insoluble hexametaphosphate, or mixtures thereof.

Agglomerated particulate abrasive materials may also be used. Preferred abrasive materials are chalk and silica, in particular silica. HAP is also a preferred additional component and especially HAP of morphology as described in WO 03/000588 (BASF) .

When employed, the total amount of abrasive is typically from 3 to 60%, in particular from 5 to 40%, and especially from 6% to 20% by weight of the total composition.

The poloxamer used in accordance with the present invention may deliver a humectancy benefit; however, it is highly preferred that compositions of the invention comprise an additional humectant such as an additional polyol, in particular an additional polyol selected from glycerol, sorbitol, propyleneglycol, xylitol, lactitol, or mixtures thereof. Sorbitol is especially preferred, this material also functioning as a sweetener (vide infra) .

When employed, the total amount of additional humectant

(i.e. excluding the poloxamer) is typically from 1 to 60%, in particular from 5 to 50%, and especially from 10% to 30% by weight of the total composition.

The composition according to the invention may comprise further ingredients. Rheological modifiers are preferred further ingredients that often contribute to the in use sensory properties of the composition. Preferred additional ingredients of this type are thickening agents, in particular cellulose derivatives (such sodium carboxymethylcellulose [SCMC]), polyethylene glycols, and thickening silicas (such as Tixosil 43 , ex Rhodia) . Other thickening agents are xanthan gum, gum Arabic, synthetic polyacrylates, and synthetic carboxyvinyl polymers (such as Carbopol^E) .

Vitamins sources, in particular sources of vitamin E, such as vitamin E acetate are a preferred further ingredient.

Additional antimicrobial agents, i.e. in addition to the zinc salt that is an essential component of compositions of the invention, may also be included. Examples include organic anti-microbials (such as triclosan or chlorhexidine) , copper salts, stannous salts (such as stannous pyrophosphate) , sanguinarine extract, metronidazole, quaternary ammonium compounds (such as cetylpyridinium chloride) , bis-guanides (such as chlorhexidine) , digluconate, hexetidine, octenidine, alexidine; and halogenated bisphenolic compounds (such as 2,2' -methylenebis- (4-chloro-6-bromophenol) ) . Anti-caries agents are further ingredients that may be advantageously employed in compositions of the invention. Examples of such agents include sodium and stannous fluoride, aminefluorides, sodium monofluorophosphate, sodium trimetaphosphate and casein.

Polymeric compounds which can enhance the delivery of active ingredients, such as antimicrobial agents, can also be included. Examples of such polymers are copolymers of polyvinylmethylether with maleic anhydride and other similar delivery enhancing polymers, e.g. those described in DE-A- 3, 942, 643 (Colgate) .

Additional non-ionic surfactants (i.e. in addition to the poloxamer, which is often classified as such) may also be included, as might cationic surfactants.

Other ingredients that may be incorporated include:

plaque buffers, such as urea, calcium lactate, calcium glycerophosphate and strontium polyacrylates;

anti-inflammatory agents, such as ibuprofen, flurbiprofen, aspirin, and indomethacin;

desensitising agents, such as potassium citrate, potassium chloride, potassium tartrate, potassium bicarbonate, potassium oxalate, potassium nitrate and strontium salts; anti-calculus agents, such as alkali-metal pyrophosphates, hypophosphite-containing polymers, organic phosphonates and phosphocitrates;

bio-molecules, such as bacteriocins, antibodies, and enzymes ;

proteinaceous materials, such as collagen;

preservatives;

opacifying agents;

colouring agents;

pH-adjusting agents;

sweetening agents, such as saccharin and sorbitol (vide supra) ;

bleaching agents, such as peroxy compounds (e.g. potassium peroxydiphosphate) ;

buffers and salts to buffer the pH and ionic strength of the composition; and

pharmaceutically acceptable carriers, e.g. starch, sucrose, water or water/alcohol systems. Water is a particularly preferred pharmaceutically acceptable carrier and is typically present in compositions of the invention at from 5 to 95%, in particular 15 to 75%, and especially at from 35 to 60% by weight of the total composition.

Examples

In the following examples, comparative examples are indicated by letters and examples according to the invention are indicated by numbers. All amounts of components are indicated as percentages by weight.

The compositions indicated in Table 1 were prepared by standard methods known in the art.

Table 1

A performance evaluation test of the compositions indicated in Table 1 was carried in order to evaluate user perceptions of the products. 20 trained panellists were employed and asked to evaluate the toothpastes across a range of attributes using a 0 to 10 line scale. The average results concerning selected attributes are indicated in Table 2.

Table 2

Compared with Example A, Example 1 gave significantly better texture in use; significantly higher flavour intensity, both in use and after use; and significantly reduced astringency after use. Compared with Example B, Example 1 gave significantly higher foam quantity and foam quality in use. The indicated differences were significant at the 95% level of confidence.

Claims

1. An oral care composition comprising a zinc salt, an anionic surfactant, an amphoteric surfactant, and a poloxamer.

2. A composition according to claim 1, further comprising an abrasive.

3. A composition according to claim 1 or 2, further comprising a humectant.

4. A composition according to any of the proceeding claims, wherein the amphoteric surfactant is a betaine.

5. A composition according to claim 4, wherein the amphoteric surfactant is a linear alkyl (Cio-Ciβ) amidopropyl betaine.

6. A composition according to any of the proceeding claims, wherein the poloxamer has a block of poly (propylene glycol) surrounded by blocks of poly (ethyelene glycol), in accordance with this formula : HO- (EO)a- (PO)_b- (EO)a-H wherein EO = CH₂-CH₂-O; PO = CH₂-CH (CH₃) -0; and a:b = from 1:2 to 5:1.

7. A composition according to claim 6, wherein the poloxamer is Poloxamer 407.

8. A composition according to any of the preceding claims, wherein the ratio of the sum of the total amounts of anionic and amphoteric surfactant to the total amount of poloxamer is from 1:2 to 2:1 by weight.

9. A method of cleaning the teeth comprising brushing with a composition according to any of the preceding claims.

10. The use of a poloxamer to improve the in use foam quantity and/or quality of an oral care composition also comprising a zinc salt, an anionic surfactant and an amphoteric surfactant.