EP1912615A2

EP1912615A2 - Composition

Info

Publication number: EP1912615A2
Application number: EP06765111A
Authority: EP
Inventors: P.A. Reckitt Benckiser Healthcare Ltd DICKSON; R.A. Reckitt Benckiser Healthcare Ltd LUCAS; A.V. Reckitt Benckiser Heathcare Ltd SPENCER
Original assignee: Reckitt Benckiser UK Ltd
Current assignee: Reckitt Benckiser UK Ltd
Priority date: 2005-07-29
Filing date: 2006-07-27
Publication date: 2008-04-23
Also published as: GB0515907D0; WO2007012850A2; WO2007012850A3

Abstract

A denture support composition in the form of a gel comprises an anionic polymer, for example a polyacrylate, and a polyvalent cation, for example zinc ions, in a carrier, wherein the composition is substantially insoluble in water.

Description

COMPOSITION

The present invention relates to a composition and method for supporting dentures in a user's mouth.

Denture wearers usually use fixatives to secure their dentures in place. Denture fixative compositions are widely available, but users encounter various problems with such products. For example many are water-soluble, leading to dissolution of the fixative over time and the dentures become loose. On the other hand, if the dentures are fixed too securely to the mouth, they cannot easily be removed. This can cause problems if, for example, small particles of food become stuck between the denture and the gum causing discomfort: if the denture cannot easily be removed, the discomfort cannot be alleviated. In addition, denture fixative compositions which do not allow easy removal may cause pain as they are pulled away from the mucosal . surface to which they have become strongly adhered.

An alternative method of securing dentures within the mouth is to provide an adhesive patch which sticks to both the mouth and the denture surface. For example, US 4503116 describes a dental adhesive device comprising a laminate of webs which are bonded together by thermoplastic ethylene oxide polymer. However such a patch is not always effective and provides no comfort benefit to the denture wearer.

A further problem suffered by denture wearers is that dentures may be ill-fitting or, when new, may take time to become comfortable in the mouth. Such problems are especially experienced by new users of dentures. A method sometimes employed by dentists when a person is first supplied with dentures is to provide a permanent cushioning pad which seats them comfortably in the mouth. However, this is not removable for the first few months, which introduces difficulties and drawbacks.

It is an object of the present invention to overcome or reduce at least one or more of the aforementioned disadvantages of present methods of retaining dentures within a user's mouth.

It is a further object of the present invention to provide for comfortable retention of dentures within a user's mouth.

According to a first aspect of the present invention there is provided a denture support composition in the form of a gel, the composition comprising an anionic polymer and a polyvalent cation and a carrier, wherein the composition is substantially insoluble in water.

The denture support composition of the invention is preferably one which allows a denture (i.e. a denture plate) to be maintained within the mouth in such a manner that it may easily be removed. Thus once in position dentures can easily be removed from the mouth and then replaced. This may be done after any period of time, i.e. there is no need to wait for the composition to dissolve or loosen.

Equally, dentures may be left in place for long periods without becoming loose or dislodged. For example they may be left in place overnight. This is of benefit in maintaining the shape of the oral cavity.

Suitably the composition has a higher affinity with the material from which the dentures are made than it does with the mucosal .surface of the mouth. Thus when the dentures are removed, the composition is preferably carried on the dentures and in preferred embodiments little or none of the composition remains within the mouth.

The gel can be spread over the denture surface and the dentures can then be placed in position in the mouth. Upon contact with saliva, the composition preferably absorbs water and may take on a putty-like and/or springy consistency.

Preferably the composition of the present invention is not a fixative composition, although dentures are held securely in place within the mouth. Unlike some of the compositions of the prior art in which dentures are fixed in one place and often cannot be moved for several hours, dentures secured within the mouth using the composition of the present invention may be removed or repositioned immediately. The composition of the invention is better termed a denture support (or cushioning) composition than a denture fixative.

The composition of the present invention is substantially insoluble in water. By substantially insoluble is meant that the composition has a solubility in water at 25⁰C of less than 100 gdm^'3, preferably less than 10 gdm^'3, more preferably less than 5 gdrrf³ and most preferably less than 1 gdπf³.

Preferably the solubility of the composition is such that after being left in the mouth for a period of 6 hours, less than 10% of the composition dissolves, and _'more preferably less than 5%.

Preferably, upon contact with an aqueous environment, the composition may absorb water and remain as a swollen gel . Water may replace the carrier in the composition and the polymer may become less soluble in water. Thus it does not wash away but remains swollen and able to provide support and/or cushioning.

Preferably the anionic polymer of the composition of the present invention comprises carboxylate residues. Preferably the anionic polymer comprises a polyacrylic acid. Such compounds are available under the trade mark Carbopol . Especially preferred are homopolymer and copolymers of acrylic acid, crosslinked with a polyalkenyl polyether .

Preferably the anionic polymer has a molecular weight of between 500,000 and 4.5 billion, more preferably between 2,000,000 and 4.5 billion. In especially preferred embodiments the anionic polymer is a polyacrylic polymer sold under the trade mark Carbopol ETD 2020.

Preferably the anionic polymer is present in the composition of the present invention in an amount of at least 1 wt%, more preferably at least 1.5 wt%, and most preferably at least 2 wt%. Preferably the anionic polymer of the present invention is present in the composition in an amount of less than 7 wt%, preferably less than 4 wt%, more preferably less than 3 wt%.

"Wt%" herein denotes weight of .the specified component/total composition weight, expressed as a percentage.

Suitably the anionic polymer, which in preferred embodiments comprises carboxylate ions, is initially provided in free acid form. Preferably therefore the composition of the present invention further comprises a base, preferably a weak base. Suitable weak bases are tertiary amines. Preferred bases are those which are pharmaceutically acceptable. Most preferably the base is triethanolamine .

Preferably the base is present in a mass excess compared to the anionic polymer. Preferably the mass of base to mass of polymer is in the range of 1.3:1 to 1.7:1.

The polyvalent cation may comprise any suitable dentally acceptable polyvalent cation.

The polyvalent cation may be trivalent, for example a cation of boron or aluminium.

Preferably it is a metallic cation.

Preferably the polyvalent cation is a divalent cation. Preferably it is a divalent cation of an alkaline earth metal or a transition metal. Especially preferred divalent cations include those of iron, zinc, magnesium, strontium, calcium, copper, manganese, cobalt or tin.

Most preferably the polyvalent cation comprises divalent zinc, Zn²⁺.

Suitably the polyvalent cation is supplied as a commonly available compound, for example a halide, oxide or hydroxide. Preferably it is supplied as a salt, for example a halide. An especially preferred salt added to the composition in order to form the polyvalent, cation is zinc chloride.

The source of polyvalent cation, for example zinc chloride, preferably provides at least 0.3 wt% of the composition, more preferably at least 0.5 wt%, most preferably at least 0.6 wt%. The source of polyvalent cation, for example zinc chloride, preferably provides less than 3 wt% of the composition, preferably less than 1 wt%.

It is believed that the polyvalent cation ionically crosslinks the anionic polymer chains. For example, it is believed that a divalent zinc ion will form one ionic bond with an anionic species (for example a carboxylate group) from one polymeric chain, and another ionic bond with an anionic species (for example a carboxylate group) of another polymeric chain.

Preferably the crosslinking of polymer chains of the present invention comprises only ionic crosslinking. Preferably there is no covalent crosslinking. Preferably the major component of the composition of the present invention is a^' pharmaceutically-acceptable carrier. Any such suitable carrier may be used, including water. Preferably the carrier is miscible with water. Preferred pharmaceutically-acceptable carriers are polyhydric alcohols, for example polyalkylene glycol, especially polyethylene glycol, and polyhydric monomeric alcohols; an especially preferred carrier is glycerol. The carrier is preferably present in an amount of at least 70 wt%, preferably at least 80 wt%.

Water may also be present in the composition, in addition to another pharmaceutically acceptable carrier. Preferably the composition comprises less than 15 wt% water, . more preferably less than 10 wt%. Preferably the composition comprises at least 2 wt% water, preferably at least 5 wt%.

The composition is preferably supplied in the form of a thick gel. The polymer is suitably solvated therein.

Preferably the composition of the present invention comprises only one polymeric compound. This may be a copolymer but is preferably supplied from a single source. Preferably no further polymeric compounds are present besides the anionic polymer.

In preferred embodiments in which the anionic polymer comprises carboxylate residues, it is preferred that the ratio of polyvalent cation to carboxylate ion is¹ such that there are free carboxylate ions i.e. there is an excess of carboxylate groups. Not all of the carboxylate groups are involved in ionic crosslinking. Preferably the extent of crosslinking is less than 50 mol%, more preferably less than 30 mol%, and most preferably less than 20 mol%. Preferably the extent of ionic crosslinking is at least 1 mol%, more preferably at least 10 mol%.

Preferably the molar ratio of carboxylate group to a divalent cation when present is at least 2:1, more preferably at least 4:1. Preferably the molar ratio of carboxylate groups to a divalent cation is less than 100:1.

Preferably the ratio of base to carboxylate groups is selected so that at least 70% of the carboxylate groups are deprotonated, preferably at least 90%, more preferably at least 95% and most preferably all of the carboxylate groups are fully deprotonated.

Clearly the compounds, grades and amounts selected should be such as to allow a gel to be formed.

The composition of the present invention may further comprise optional excipients for example colorants or flavouring and the like.

Preferably the composition contains up to 4 wt% (total) of extracts from plants, able to provide a sensory and/or therapeutic benefit, for example by promoting healing or providing soothing. Suitable extracts may include mentha piperita, menthol, lemongrass, bitter fennel oil, sage oil, chamomile and clove oil.

Preferably the composition of the present invention consists essentially of an anionic polymer, a base, a source of polyvalent cation, water and a pharmaceutically acceptable carrier: any further components are present as only as minor cosmetic excipients. ■ .

According to a second aspect of the present invention there is provided a method of supporting a denture in position within the mouth, the method comprising the steps

Of:

a) application to the denture of the composition of the first aspect; and b) positioning of the denture within the mout,h.

Preferably the dentures are retained in the mouth overnight and thereby maintain the oral cavity in a good shape .

Although the denture may be securely supported within the mouth, it may also be removed easily.

The composition of the present invention is preferably in the form of a thick gel which is applied to the dentures and is of sufficient "stickiness" to hold them in place.

According to a third aspect of the present invention there is provided the use of a composition of the first aspect in order to support dentures in position within the mouth.

According to a fourth aspect of the present invention there is provided a process for preparing a composition of the first aspect, the process comprising the steps of: a) addition, to an acid precursor of the anionic polymer, of a pharmaceutically-acceptable carrier and stirring for a first period of time; b) addition of a base and stirring for a second period of time; c) addition of an aqueous solution comprising the polyvalent cation; d) stirring of this reaction mixture for a third period of time; and e) optionally adding further excipients.

The first period of time for stirring in step a) is preferably at least 10 minutes, more preferably at least 15 minutes, and preferably less than 40 minutes, more preferably less than 30 minutes.

The second period of time of stirring in step b) is preferably at least 10 minutes, more preferably at least 15 minutes, and preferably less than 40 minutes, more preferably less than 30 minutes.

The third period of time of stirring in step d) is preferably at least 15 minutes, more preferably at least 20 minutes, and preferably less than 1 hour, more preferably less than 45 minutes.

Preferably all of the steps of the process of the fourth aspect of the present invention are carried out at ambient temperature .

The invention will now be further described with reference to the following non-limiting examples. Example 1

A denture support composition was prepared comprising the following components:

Carbopol ETD 2020 2.5 wt% Triethanolamine 3.68 wt% Glycerol 84.575 wt% Water 8.46 wt% Zinc chloride 0.72 wt%

Mentha piperita 0.05 wt%

Menthol 0.01 wt%

Lemongrass mint flavour 0.005 wt%

Method:

• add the Carbopol to the glycerol and stir for 20 minutes at room temperature

• add the triethanolamine and stir for 20 minutes • add the zinc chloride (as a solution in water) to the mixture

• add the flavors and stir for a further 30 minutes at room temperature before packaging.

The composition was found to provide excellent support and cushioning properties. The dentures were easily removed and carried on them the composition. The dentures could then be cleaned easily. The herbal components give sensory and/or natural therapeutic benefits. Example 2

A denture support composition was prepared, in the manner described in Example 1, comprising , the following components :

Carbopol ETD 2020 2.5 wt% Triethanolamine 3.68 wt% t Glycerol 82.33 wt%

Water 8.46 wt%

Zinc chloride 0.72 wt%

Mentha piperita 0.0985 wt%

Menthol 0.02 wt% Chamomile extract 2.0 wt%

Sage oil 0.1 wt%

Bitter fennel oil 0.1 wt%

Again, good properties were obtained, and the herbal components gave sensory and/or natural therapeutic benefits.

Claims

1. A denture support composition in the form of a gel, the composition comprising an anionic polymer and a polyvalent cation and' a carrier, wherein the .composition is substantially insoluble in water.

2. A denture support composition as claimed in claim 1 wherein the anionic polymer comprises carboxylate functional groups.

3. A denture support composition as claimed in claim 2 wherein some carboxylate groups are used, with the polyvalent cation, in ionic cross-linking and others are not .

4. A denture support composition as claimed in claim 2 or 3 wherein the anionic polymer comprises a polyacrylic acid (as homopolymer or a copolymer) which has been at least partially deprotonated.

5. A¹ denture support composition as claimed in any preceding claim wherein the polyvalent cation comprises a divalent cation of an alkaline earth metal or a transition metal.

6. A denture support composition as claimed in claim 5 in which the polyvalent cation is divalent zinc, Zn .²2+

7. A denture support composition as claimed in any preceding claim which further comprises a base.

8. A denture support composition as claimed in claim 7 in which the base is triethanolamine .

9. A denture support composition as claimed in any preceding claim in which the carrier comprises a polyhydric alcohol .

10. A denture support composition as claimed in claim 9 in which the carrier comprises a polyhydric alcohol and water.

11. A denture support composition as claimed in any preceding claim which comprises 1-7 wt% of an anionic polymer, 0.3-3 wt% of a compound which supplies the polyvalent cation and at least 70 wt% of a carrier.

12. A method of supporting a denture in position within the mouth, the method comprising the steps of:

a) application to the a denture of a composition as claimed in any preceding claim,- and b) positioning of the denture within the mouth.

13. Use of a composition as claimed in any of claims 1 to 11 in order to support a denture in position within the mouth.

14. A process for preparing a composition of as claimed in any of claims 1 to 11, the process comprising ^• the steps of: a) addition, to an ' acid precursor of the anionic polymer, of a pharmaceutically-acceptable carrier and stirring for a first period of time; b) addition of a base and stirring for a second period of time', to effect partial or total deprotonation of the acid precursor; c) addition of an aqueous solution comprising the polyvalent cation; d) stirring of this reaction mixture for a third period of time; and e) optionally adding further excipients.

15. A composition, method, process or use as hereinbefore described, with reference to the examples.