AU6096998A - Mouthwash composition - Google Patents

Description

MOUTHWASH COMPOSIΗON

The present invention relates to mouthwash compositions, in particular compositions comprising the cationic antibacterial agent, chlorhexidine. WO 93/16681 discloses oral hygiene compositions including mouthwashes comprising cationic antibacterial agents such as chlorhexidine and as an anti-staining agent polyvinyl pyrrolidone (PVP).

It has now been discovered that a two phase chlorhexidine/PVP mouthwash having a particular pH range exhibits enhanced chlorhexidine efficacy. Accordingly in a first aspect the present invention provides a mouthwash composition comprising two phases; a first phase comprising chlorhexidine or an orally acceptable acid addition salt thereof and an orally acceptable carrier or excipient and a second phase comprising PVP and an orally acceptable carrier or excipient; the two phases being kept separate until use, whereupon on mixing they provide a single phase having a pH between 6 and 10.

It is advantageous to separate the chlorhexidine and PVP phases until use since it has been discovered that the efficacy of chlorhexidine can otherwise be reduced upon long term storage with PVP.

The pH of the chlorhexidine phase and the PVP phase are such that on mixing they result in a pH from 6.0 to 10.0, preferably 6.0 to 9.0, more preferably 6.0 to 7.0, eg 6.2.

Conveniently equal amounts, by weight, of the chlorhexidine and PVP phases are mixed prior to use.

Suitably the initial pH of the chlorhexidine phase is no greater than 6 which has the advantage of increasing the long term storage stability of chlorhexidine.

Preferably the initial pH of the chlorhexidine phase is from 3.0 to 6.0, more preferably 5.0 to 5.9 for example 5.5 to 5.9.

Suitably the pH of the PVP phase is from 6.0 to 10.0, preferably from 6.0 to 9.0, more preferably from 6.0 to 8.0. Preferably the PVP phase comprises an orally acceptable buffer or pH modifier such that on mixing with the chlorhexidine phase the desired pH is obtained.

Examples of orally acceptable buffers and pH modifiers include a base such as sodium hydroxide, or an acid such as acetic, gluconic, tartaric, citric, lactic, or phosphoric acid or a soluble salt thereof. These can be used individually or as mixtures. A preferred buffer is sodium acetate.

The buffer or pH modifier should be present in sufficient quantity to provide the desired buffering effect, suitably from 0.01 to 10%, preferably from 0.1 to 2% by weight of the composition.

The compositions of the present invention can be packaged into a container such as a bottle or tube having two chambers for separating each phase, the container having a dispensing nozzle allowing controlled dispensing and suitably concomitant mixing of said prior phases to use. Alternatively such compositions can be packaged into a sachet having two chambers separated by a frangible seal which can be ruptured prior to use allowing mixing of the two phases within the sachet.

Alternatively the two phases may also be packaged in separate containers which can dispense the required amount of each phase prior to mixing and use. Polyvinyl pyrrolidone for use in the present invention suitably has an average molecular weight of at least 5,000 eg in the range 5,000 to 100,000, preferably in the range 5,000 to 50,000. Polyvinyl pyrrolidones which have average molecular weights of 10,000, 30,000 and 40,000 are available from Sigma Chemical Co., GAF Corporation and Sigma Chemical Co. respectively. Polyvinyl pyrrolidone is suitably present in at least 0.5%, preferably between 0.5 and 30%, more preferably between 0.5 and 25%, and advantageously between 1 and 15% by weight of the composition.

Suitably, chlorhexidine or an orally acceptable acid addition salt thereof is present in from 0.005 to 10% preferably 0.01 to 5%, more preferably 0.01 to 2%, by weight of the composition. Suitable salts of chlorhexidine include those which have a solubility at 20°C of at least 0.005% w/v and include the digluconate, diformate, diacetate, dipropionate, dihydroiodide, dihydrochloride, dilactate, dinitrate, sulphate, and tartrate. Of these, the digluconate, diacetate and dihydrochloride are favoured. The compositions of the present invention may also usefully contain an ionic fluorme-containing compound. Suitable ionic fluorine-containing compounds include, for instance, fluoride salts such as amine fluorides and alkali metal fluoride salts, for example sodium fluoride, and monofluorophosphate salts such as alkali metal monofluorophosphate salts, for example sodium monofluorophosphate. Suitably the ionic fluorme-containing compound is incorporated into the composition to provide between 50 and 2000ppm, preferably between 100 and 500ppm of fluoride ions.

The compositions of the present invention will suitably comprise as components of the carrier a surfactant and optionally a humectant, preferably in an aqueous or an aqueous/ethanol solution.

It will be appreciated by those skilled in the art that in order to ensure that the antibacterial efficacy of chlorhexidine is not substantially diminished, compatible components will be selected for inclusion in the orally acceptable carrier or excipient. Accordingly, where necessary anionic species should be preferably avoided as such species may cause inactivation of the chlorhexidine by the formation of an insoluble precipitate therewith. Thus, anionic surfactants and anionic humectants should preferably be rejected in favour of non-anionic counterparts such as nonionic, cationic or amphoteric surfactants and nonionic humectants. Suitable nonionic surfactants include, for example, polyethoxylated sorbitol esters, in particular polyethoxylated sorbitol monoesters, for instance, PEG(40) sorbitan di-isostearate, and the products marketed under the trade name 'Tween' by ICI; polycondensates of ethylene oxide and propylene oxide (poloxamers), for instance the products marketed under the trade name 'Pluronic' by BASF-Wyandotte; condensates of propylene glycol; polyethoxylated hydrogenated castor oil, for instance, cremophors; and sorbitan fatty esters. Suitable amphoteric surfactants include, for example, long chain imidazoline derivatives such as the product marketed under the trade name 'Miranol C2M' by Miranol; long chain alkyl betaines, such as the product marketed under the tradename Εmpigen BB' by Albright + Wilson, and long chain alkyl amidoalkyl betaines, such as cocamidopropylbetaine, and mixtures thereof.

Suitable cationic surfactants include the D,L-2-pyrrolidone-5-carboxylic acid salt of ethyl-N-cocoyl-L-arginate, marketed under the trade name CAE by Ajinomoto Co. Inc.

Preferred surfactants include the nonionic poloxamers and polyethoxylated hydrogenated castor oils.

It has been discovered that the compatibility of such surfactants with chlorhexidine is further enhanced if the pH of the combined phase is between 6 to 10, preferably between 6 to 8.

Advantageously, the surfactant is present in the range 0.005 to 5%, preferably 0.005 to 1 % , more preferably 0.01 to 0.5 % by weight of the composition.

Suitable humectants for use in compositions of the invention include for instance glycerin, sorbitol, propylene glycol or polyethylene glycol, or mixtures thereof. The humectant may be present in the range from 5 to 70%, preferably 5 to 30%, more preferably 5 to 20% by weight of the composition.

Other materials may be added to the compositions if required, for instance sweetening agents, flavouring agents, colouring agents, preservatives and emulsifiers.

Suitably the PVP phase comprises a sweetening agent such as sodium saccharin which is advantageously kept separate from the chlorhexidine phase thereby preventing unwanted precipitation of a chlorhexidine/saccharin complex on long term storage.

The compositions according to the present invention may be prepared by mixing the ingredients thereof in the required proportions and in any order that is convenient and thereafter and if necessary adjusting the pH to the required value. The compositions according to the present invention are of use in reducing or eliminating the stain normally associated with the use of chlorhexidine.

Accordingly, in a further aspect, the present invention provides a mouthwash composition as hereinbefore defined for use in therapy, in particular anti-plaque, anti-caries, anti-calculus and/or periodontal (including anti-gingivitis) therapy.

The invention will now be illustrated by reference to the following examples.

Example 1 Chlorhexidine Mouthwash

^♦Cremophor RH60 is a polyethoxylated hydrogenated castor oil containing on average 60 ethoxy units in the polyethoxylated chain.

Example 2 The Effect of pH on Chlorhexidine binding to saliva coated Hydroxyapatite discs from mouthwashes

It is well known in the art that the binding of chlorhexidine to hydroxyapatite is an effective indicator of activity in the oral cavity as chlorhexidine's effectiveness is due to its ability to bind to oral surfaces.

The following test method can be used to determine the level of binding of chlorhexidine to hydroxyapatite in vitro :- a)Hydroxyapatite discs of known surface area are soaked overnight in sterile, filtered pooled human saliva at 37 C. b)The discs are then rinsed for 15secounds in 25ml of deionised water. c)Each disc is then treated for 60 seconds by submerging it in 5 ml of the test solution followed by 3 washes for 60 seconds duration in 25ml aliquots of deionised water. d)Bound chlorhexidine is then extracted from the disc and analysed by HPLC.

To assess the effect of pH on the binding of Chlorhexidine the control solutions and mouthwashes detailed in Tables 1 and 2 were prepared. The products were then assessed for Chlorhexidine binding using the method outlined. The results obtained are shown in Table 3.

Tahle 1

Xable_2

Tabled

The results show that binding significantly increases from pH 5.6 (mouthwash 5) to pH 6.2 (mouthwash 6). As the pH increases from 6.2 to 9.5 (mouthwashes 6-10) no further significant differences between the products are observed.

This experiment demonstrates that enhanced binding can be achieved if a mouthwash is delivered with a pH of greater than 6.

Claims (10)

Claims

1. A mouthwash composition comprising two phases; a first phase comprising chlorhexidine or an orally acceptable acid addition salt thereof and an orally acceptable carrier or excipient and a second phase comprising PVP and an orally acceptable carrier or excipient; the two phases being kept separate until use, whereupon on mixing they provide a single phase having a pH between 6 and 10.

2. A composition according to claim 1 wherein the pH of the chlorhexidine phase and the PVP phase are such that on mixing they result in a pH from 6.0 to 8.0.

3. A composition according to claims 1 or 2 wherein the pH of the chlorhexidine phase is no greater than 6.

4. A composition according to any one of claims 1 or 3 wherein pH of the PVP phase is from 6.0 to 10.0.

5. A composition according to claim 4 wherein the PVP phase comprises an orally acceptable buffer or pH modifier such that on mixing with the chlorhexidine phase the desired pH is obtained.

6. A composition according to any one of claims 1 or 5 wherein the PVP is present in at least 0.5% by weight of the composition.

7. A composition according to any one of claims 1 to 6 further comprising an ionic fluorine-containing compound.

8. A composition according to any one of claims 1 to 7 comprising a nonionic, amphoteric or cationic surfactant.

. A composition according to claim 8 wherein the surfactant is a nonionic poloxamer or polyethoxylated hydrogenated castor oil.

10. A composition according to claim 8 or 9 wherein the surfactant is present in the range 0.005 to 5 % by weight of the composition.