Drug – bio-affecting and body treating compositions – Anti-perspirants or perspiration deodorants
Reexamination Certificate
2002-03-13
2004-05-18
Dodson, Shelley A. (Department: 1616)
Drug, bio-affecting and body treating compositions
Anti-perspirants or perspiration deodorants
C424S066000, C424S068000, C424S400000, C424S401000, C514S937000, C514S938000
Reexamination Certificate
active
06737048
ABSTRACT:
BACKGROUND TO THE PRESENT INVENTION
The present invention relates to antiperspirant formulations for topical application and in particular to formulations in the form of emulsions.
Humans perspire aqueous sweat through eccrine glands in the course of exercise or as a consequence of emotional stress. In certain areas of the body such as underarm, there is an especially high surface density of eccrine glands which can result in sweat becoming visible, either on the skin itself or by absorption by clothing which comes into contact with the skin in the vicinity of the armpits. In many societies, people wish to avoid the sweat being visible, at least on some areas of the body such as underarm, and accordingly apply topically antiperspirant formulations to those selected areas.
Many antiperspirant formulations which have been developed or/and commercialised comprise an astringent salt, such as an astringent aluminium and/or zirconium salt in a suitable carrier system. Applicators for the formulations can be classified as either contact or non-contact applicators. Non-contact applicators are especially hygienic because there is no contact between the dispenser and the human body in the vicinity of where the formulation is to be applied, but many consumers desire to use contact applicators, especially in North America.
Formulations for contact applicators can themselves be classified into three broad types, based on their physical characteristics. One type comprises lotions, which flow under gravity and are commonly dispensed using a roll-on applicator. A second type comprises a cream or soft solid which commonly have sufficient inherent structure that they either flow very slowly or retain their shape when they are not subjected to pressure, but which flow under pressure. These are commonly dispensed through an applicator comprising a container for the formulation, a perforated cap for the container through which the formulation can flow and a means to pressurise the formulation and urge it towards the perforated cap. A third type comprises a firm stick, which is structured sufficiently to maintain its integrity even when subjected to gentle pressure.
The structured formulations can themselves be further classified into three classes. One class comprises solution formulations. As the name suggests, the active constituent is dissolved in the carrier fluid. In a second class, which comprises suspension formulations, the active constituent is not soluble in the carrier fluid and is present in the form of suspended particles. In the third class, the formulation comprises an emulsion in which droplets of one liquid phase, the internal phase, are dispersed within a continuous second liquid phase, the external phase. Commonly, in respect of antiperspirant formulations, one of the phases is hydrophobic and the other is hydrophilic and the active material is dissolved in the hydrophilic phase. The instant invention relates particularly to the third class, namely structured formulations in the form of such emulsions.
Consumers have regard to many different aspects of antiperspirant products when making their choice from which are products available. These include a choice between contact and non-contact applicators, the physical attributes of an antiperspirant formulation, such as lotion, cream or firm stick and whether it is efficacious. However, they have regard to the aesthetics of the product, such as its appearance and the skin sensations on application of the product, especially when contemplating a repeat purchase. In other words, they take into the account the sensory and visual characteristics of the product. The various different sensory characteristics include whether the formulations feels cool or not on application, whether it feels dry or wet on application, whether it feels sticky, the smoothness with which a contact formulation glides across the skin and whether it feels greasy.
It is a continuing objective of producers of antiperspirant formulations to meet the evolving needs or preferences of their consumers. In that context, the inventors have carried out further investigations into structured antiperspirant emulsions. It will be recognised that emulsions represent comparatively complex systems for delivering an antiperspirant to the skin with inter-relationships between various of the formulation constituents. In common with non-emulsion formulations, there are constraints on the proportions of the various components which can be employed. For example, increasing the proportion any particular constituent reduces the formulation headspace for other constituents, but can also impact upon the efficacy and aesthetics of the product.
However, for emulsions, there is additionally the complication of there being two liquid phases, in both of which their constituents can be varied as well as the volume or weight ratio between the two of them being varied. It will also be recognised that the antiperspirant in an emulsion is commonly a constituent of a disperse hydrophylic phase. The inventors have identified that in order for the antiperspirant active to be effective, the disperse phase should be brought into close contact with the skin in the vicinity of its sweat-producing eccrine glands. The inventors have further found that varying the constituents of one phase may not only change a target functional attribute, but at the same time may also change either the aesthetics or appearance of the product as well, possibly in a manner which is less attractive to consumers. For example, changing the proportion of antiperspirant active solution in the formulation not only can have the effect of changing the efficacy of the product, but can simultaneously change the feel of the product and changing the relative or absolute amounts or the nature of constituents of either phase can alter the appearance of the product. Consequently, the inventors have not only found that there are several relationships between the components of structured emulsions which should be taken into account when seeking to produce an emulsion product, but also that to at least some extent, they can conflict with each other.
It is inherently desirable to produce a product having both acceptable efficacy and acceptable aesthetic attributes. Consequently, when making changes to a formulation in order to improve or optimise the product in one regard, be it sensory properties or efficacy, it is a practical desideratum that such changes do not impair to a significant extent the other properties of the product.
Structured hydrophylic emulsion antiperspirant formulations have been described in a series of recently published PCT applications to Unilever plc et al, including particularly WO00/61079, WO00/61081, WO00/61094 and WO00/61096. In particular, these specifications gave descriptions of various constituents which can be employed in antiperspirant emulsions, including antiperspirant actives, structurants, emulsifiers, constituents of the hydrophylic and non-hydrophylic phases and how to make such emulsions.
Various generalised ranges are given for the components of the structured antiperspirant emulsions and many different structured antiperspirant emulsion formulations are described in the aforementioned Unilever specifications, but there is no direct teaching therein as to which combinations of ingredient proportions have superior and which have inferior efficacy and/or sensory properties. Consequently, the problem remains as to how to select structured antiperspirant emulsions which can provide an improved balance of antiperspirant activity and sensory properties. In other words, the problem remains of how to avoid or ameliorate impairment of sensory properties when improving or maintaining efficacy at the same time as avoiding or ameliorating impairment of efficacy when improving or maintaining sensory properties.
SUMMARY OF THE PRESENT INVENTION
A structured antiperspirant emulsion comprising an hydrophilic phase containing an aluminium and/or zirconium astringent salt dispersed in a continuous oil phase comprising
Abend Sven Jorg Willi Max
Courtois Jean-Philippe Andre Roger
Cropper Martin Peter
Fletcher Neil Robert
Grainger Lynda
Dodson Shelley A.
Stein Kevin J.
Unilever Home & Personal Care USA , division of Conopco, Inc.
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