GB2182339A - Buffered thickening agents for protective cleansing lotions - Google Patents

Abstract

A buffered thickening agent, for use in cleansing lotions or in topically applied medicaments or cosmetics, comprises a naturally occurring gum, such as a Xanthan gum, and an orthophosphate buffer. The buffer thus acts to increase the viscosity of the gum in use so that higher ionic concentrations can be tolerated without destabilisation of the emulsion when the buffered thickening agent is formed into a lotion. Preferably the buffered agent constitutes 0.5% to 2% by weight of an oil-in-water protective cleansing lotion which may also comprise 10% to 20% by weight of petrolatum.

Description

SPECIFICATION Protective cleansing lotions and buffered thickening agents for use therewith The present invention relates to protective cleansing lotions, and particularly to buffered thickening agents for use therewith. Such lotions are of particularvalue in infant care, butofcourse have a wider range of use in medicinal and cosmetic applications.

The use of greasy skin protectives has long been used in infant care to protect an infant's skin, interalia, adjacent the'nappy' area. Vaseline (Registered Trade Mark) is a pharmaceutically acceptable form of Petro latum and is often used forthis purpose, although it suffers the disadvantage that because it is greasy it is unpleasant to use, although moderately effective. Other drying agents such as talcum powder etc. are also used to make an infant's skin as dry as possible in orderto protect against nappy rash etc. butthis is not particularly effective. Both these traditional measures are of limited use since the Vaseline tends to protect, although not really to dense, while powders tend to cleanse but have a limited protective role.

Other attempts at providing combined protective cleansing creams for use in infant care have been tried; one such being available as Milton Milguard. This product acts at the environment of use in partto protectthe skin by means of a protective agent, and in part by the inclusion in the composition of a bufferto maintain the composition at a non-irritant pH of between 6 and 7 and which tends to neutralise the alkaline products present in urine.

Effective buffering of such compositions is dependent upon the amount of ionic concentration which can be present in the composition without destabilising the emulsion. Accordingly, the prior art protective lotions are of limited protective value since although they can physically protect the skin by means of a film there- upon, the power of the buffering system which can be included therein is of a low order.

According to the present invention therefore there is provided a buffered thickening agent for use in a topically applied medicament or cosmetic, said thickening agent comprising a naturally occurring gum and an orthophosphate buffer, wherein the buffer also acts to increase the viscosity of the gum. It will be appreciated that where the buffer also acts to increase the viscosity ofthe gum higher ionic concentrations can be tolerated without destabilisation of the emulsions and hence a greater protective effect is experienced at the environment of use.

The gum is preferably a Xanthan gum which may be used alone or in conjunction with a secondary thicken ing agent which reacts with a bodilyfluid atthesite ofintended use to renderthe same insoluble. Such a secondary thickening agent may be an alkali metal alginate such as sodium alginate. The buffermaybe selected from sodium dihydrogen orthophosphate or di-sodium hydrogen orthophosphate or a mixture thereof. Such a buffer system will maintain the lotion into which it informed at a pH of about6.5.

In another aspect of the invention there is provided an oil-in-water protective cleansing lotion comprising from 10% tp 20% by weight of petrolatum, and from 0.5% to 2% by weight of buffered thickening agent asjust described. Because of the beneficial effect of the thickening, and particularlyXanthan gum, only small amounts of emulsifiers need be used. An acceptable quantity is in the range 0.3%to 1% and preferablyabout 0.6% in total. Such emulsifiers may be selected from monostearates known forthis purpose and particularly glyceryl monostearate and/or sorbitan monostearate.

The oil portion of the oil-in-water phase may in addition to the naturally occurring gum include a hypoallergenic lanolin and/or a high viscosity silicone fluid.

When sodium alginate is used as a secondary thickener, it will be converted to calcium alginatefollowing contact with urine in the nappy area since an infant's diet contains a high proportion of calcium ions. This calcium alginate is of course insoluble in water and hence essentially non-irritant.

The invention will now be described, byway of illustration only, in the following example and accompanying drawing. The accompanying drawing shows a graph indicating the neutralisation of ammonia by a composition in accord with the present invention as compared with that of the prior art.

Example 1.

Acleansing lotion formulation was made upto consistofthefollowing : Percentage (wiz) Petroleum (Snowhite EC) 14.0 Croda Refined Lanolin Ester 1.0 Dowcoming Silicone oil DC 200m (1000 cps) 1.0 Croda Self-Emulsifyiung glyceryl monstearate (SEGMS) 0.6 Croda Crill 3 (Sorbitan monostearate; Emulsifier) 0.3 KeltrolF(Kelco) or )Xanthan Gum Primary May and Baker )thickening agent 0.6 Example 1. (continued) Acleansing lotion formulation was made up to consist ofthefollowing:- Percentage (wiz) Mannucol DM (Kelco; Sodium Alginate) 0.13 (SecondaryThickening Agent) Sodium dihydrogen orthophosphate (Buffer) 0.2 Di-sodium hydrogen orthophosphate (Buffer) 0.1 Germall 115 (Imidazolidinyl urea;Preservative) 0.55 Postassium Sorbate 0.2 EDTA as di-sodium Salt 0.05 Demineralised water to 100 The formulation was made up as follows: The water was heated to 60"C and the Mannucol was dispersed and dissolved therein with high speed stirring, followed by dispersion and dissolution ofthe Keltrol F, again at high speed.

Heating was then continued to 75"C. Whilst this aqueous phase was being prepared, the oil phase was mixed in a separate vessel. The petroleum was first heated and melted before the refined lanolin and silicone oil were added with low speed stirring.The Emulsifies (SEGMS and Crill 33) were then dissolved thereinto 60"C. The oil phase was then heated further to 75"C. The oil and water phases were then admixed with high speed stirring in conjunction with high shear mixing such as by a Silvercome mixer.

Air incorporation should be avoided since the lotion has a significant viscosity which increased the op- portunity ofairentrappment.

The preservatives and phosphate salts were then dissolved in water and mixed into the emulsion at400C.

This has a considerable thickening effect.

The lotion was then bottled. The lotion is pseudoplastic and hence will then when pumped.

Properties Thick white lotion, pH 6.5 viscosity ca 50,000 cps at 0.5 rpm (Brookfield RVT Spindle 5) ca 640 cps at 100 rpm.

Example 2.

Cleansing Lotion and formulation. A cleansing lotion formulation was made up in a similarfashion to Example 1 and comprised the following ingredients: Ingredient Percentage (wiz) 1. Petrolatum (Witco Snowhite EC) 14.0 2. Supersterol ester (Croda CH 4986) (hypoallergenic lanolin) 1.0 3. Silicone Oil (Dow Corning 200; 1000cs) 1.0 4. Self-emulsifying glyceryl monostearate (SeppicSimulsol 165-CheshamChemical) 0.4 5. Sorbitan monstearate (Emulsifier) 0.2 (Croda Crill 3) 6. Xanthan gum (primarythickening agent) (Kelco Keltrol) 0.6 7. Sodium alginate (secondarythickening agent) (Kelco Manucol DM) 0.13 8. Sodium dihydrogen orthophosphate (Buffer) 0.20 9. Di-sodium hydrogen orthophosphate (Buffer) 0.12 10. Germail II (Preservative) (Sutton Labs Inc: Blagden Campbell in UK) 0.30 11. Methyl parahydroxybenzoate (Preservative) 0.1 12. Propyl parahydroxybenzoate (Preservative) 0.1 (Nipa Labs) 13. Water to 100 Final pH = 6.5 Example 3.

The cleansing lotion of Example 2 wastested for neutralisation of ammonia againstthe nearestavailable cleansing lotion currently available, namely Milton Milguard. Results are shown in the accompanying draw ing wherein it will be seen that products in accordance with the present invention has a buffering capacity approximately seven times greaterto a pH of 8than thatofthe prior art.

Itwill also be seen from the formulation of Examples 1 and 2that no humectants are required. Theseare undesirable in that they can tend to dry out the skin in conditions of low humidity. Further, humectants are potential sensitisers and also act to assist skin wash off of the lotion which is precisely the effect which the present invention seeks to avoid.

In accordance with the present invention, therefore, there is provided a lotion which is buffered to a slightly acidic pH which matches the natural pH of the skin thereby to minimise irritation thereof. This natural buffering system also neutralises ammonia which is well known to initiate nappy rash. The lotion made in accord with the present invention does not require solubilising oils which tend to remove the skin's natural protect- ive oils and increase the skin's susceptibility to irritation and infection. Further, because the lotion is thickened with naturally derived gums the need for high concentrations of emulsifiers is reduced whilesatisfactory thickness, i.e. viscosity, is attained. These naturally occurring gums also help to form a barrier to waterborne irritants on the skin and hence further reduce the incidence of nappy rash.

Accordingly, the present invention relates to buffered thickening agents for use generally with lotions for application to the skin, and to specific lotions including such agents.

Claims (9)

1. Abuffered thickening agentforuse in a topically applied medicamentorcosmetic, said thickening agent comprising a naturally occurring gum and an orthophosphate buffer, wherein the buffer also acts to increase the viscosity of the gum.

2. An agent according to claim 1 wherein the gum isa Xanthan gum.

3. An agent according to either of claims 1 or 2 additionally comprising a secondarythickening agent which is adapted to insolubilise reactants in a bodily fluid at an environment of use.

4. An agent according to claim 3 wherein the second thickening agent is an alkali metal alginate.

5. An agent according to any preceding claim wherein the buffer is selected form sodium dihydrogen orthophosphate or di-sodium hydrogen orthophosphate.

6. A bufferthickening agent substantially as hereinbefore described with referenceto Example 1.

7. An oil-in-water protective cleansing lotion comprising from 10% to 20% by weight of petrolatum, and from 0.5% to 2% by weight of a buffered thickening agent as claimed in any one of claims 1 to6.

8. A lotion according to claim 7 comprising a maximum of 1% by weight of emulsifier.

9. A lotion according to claim 7 and substantially as herninbeforn set forth with reference to the foregoing Example.