Drug – bio-affecting and body treating compositions – Dentifrices
Reexamination Certificate
2001-08-21
2003-01-14
Dees, Jose′ G. (Department: 1619)
Drug, bio-affecting and body treating compositions
Dentifrices
C424S401000
Reexamination Certificate
active
06506367
ABSTRACT:
The present invention relates to an oral composition.
Co-ground products are known in the pharmaceutical field for providing improved solubility to particular agents. Such products have improved dissolution rates when the product is wetted. Typical products are described in EP 0 371 431 (Vectorpharma) where an active substance is mixed with a support substance and co-ground in a mill. The end product is then dried before it can be used.
Co-grounds have also been disclosed for topical cosmetic purposes. WO 99/17736 (Telos) describes how amorphisation results in much a higher solubilisation kinetics profile, in conditions of supersaturation, compared with using the crystalline forms of an active. The co-ground typically comprises a binary system of a carrier, which may or may not be inert, and a cosmetic active material which typically has poor solubility characteristics. The two materials are ground together in the absence of a solvent. The cosmetic actives proposed for co-grinding are solids, or have been rendered solid via absorption, inclusion or microcapsulation. Suitable carriers with which the actives can be co-ground include organic materials such as starches, polyvinyl pyrrolidone, and phospholidpids to name a few, while inorganic examples include, talc, titanium dioxide, zinc oxide, kaolin, zeolites, siO2, silica gel, calcium phosphate, calcium carbonate and the like. This prior art also discloses how the co-grounds can be made by milling, preferably in a high energy mill.
The prior art also discloses in U.S. Pat. No. 4,098,878 (Baines) that co-grinding is one of a number of possible routes by which an abrasive particle for use in toothpaste may be surface-modified with a fatty acid. The abrasive is disclosed to have different reactive properties when modified during the chosen process. Essentially, the surface modification is a means to mask the reactive groups on the abrasive particle and the surface modifying agent is added only in very small amounts, preferably as little as possible, to coat the abrasive particle. In a way it is a form of encapsulation. This patent also states that the modifying agent is added at from 0.1 to 5% by weight of the abrasive particle.
U.S. Pat. No. 4,346,072 (Baines) discloses a similar technology but states that the amount of surface-modifying agent is from 0.1 to 0.5% by weight of the abrasive.
We have surprisingly found that co-grinding technology can be successfully used in oral care formulations which comprise water and where the co-ground comprises at least two ingredients each of which are present at more than 5% by weight of the total co-ground. It is disclosed in the prior art (Telos) that the co-grounds have improved wettability so it is quite surprising that these can be included in hydrous formulations. In fact, a co-ground ingredient can be included in an oral care formulation with surprising stability despite the presence of water as well as surfactants and ionic materials which would typically interfere with the stability of a material. The prior art mainly teaches that powders can be formulated which, when put into contact with a wet surface, have improved solubility/wettability characteristics. The prior art also teaches that co-grinding may be used to apply small amounts of a surface modifying agent to an abrasive particle.
The invention is thus a particularly useful technological advance in oral care as regulatory affairs and consumer sensory perception play an enormous part in the selection of ingredients. For example, there exist many materials, which have a relatively high efficacy but are not used because they taste unacceptably to the consumer. For example, chlorhexidine is an efficacious anti-microbial material, which is hardly ever used in oral care compositions because of its poor taste, which obviously presents an overwhelming consumer negative. On the other hand, there are some materials, which are virtually essential in oral care technology but have a noticeable negative effect on some of the other materials which could provide a consumer benefit. For example, sodium lauryl sulphate (SLS) is a preferred foaming agent in oral care compositions. Unfortunately, SLS has a negative effect on the efficacy of cationic anti-microbial materials such as cetylpyridinium chloride. As such, these materials cannot be used to their fullest in oral care.
Accordingly, we have surprisingly found that the inclusion of co-ground products in oral care formulations can provide an improvement for the consumer, depending upon the ingredients chosen in the co-ground. For example, the use of flavours in a co-ground can provide improved or even prolonged flavour release. Actives which are unstable in the presence of common oral care ingredients such as surfactants can now be used in a co-ground to provide a previously unattainable benefit. This has the further advantage that ingredients which were unstable in the presence of each other but which were stored independently in separate chambers until use may now be formulated in a single tube thus providing a cheaper product. Further, ingredients which were not included in commercially available oral care products before now because of poor sensory perception, e.g. taste or low-foaming, may now be included in a co-ground form which alters the perception profile and provides an improved benefit to the consumer.
A first aspect of the invention thus provides an oral composition comprising a co-ground of at least two ingredients which are co-ground without the use of solvents and wherein the co-ground comprises each of at least two ingredients at a level of at least 5% by weight of the total weight of the co-ground, characterized in that the composition is an aqueous toothpaste composition.
The composition according to the invention is an aqueous composition and comprises from 1 to 80%, preferably from 3 to 50%, more preferably from 5 to 30% by weight water.
By ‘co-ground’ is meant that at least two materials (a carrier and an active) are ground in a mill without the use of solvents as is described in WO 99/17736 the contents of which are incorporated herein by reference, particularly with respect to the nature and the making of co-grounds. However, for the sake of clarity a co-ground is a ground particle, which comprises at least two ingredients, which have been milled together in the absence of a solvent.
The co-grinding process is carried out in a conventional apparatus, such as a ball mill, a cylinder mill, a rotary mill, a grinding mill or a vibrational mill, for times ranging from a few minutes to some hours, for example from 30 minutes to 8 hours. Preferably, the co-grinding process is carried out in a mill which translates vibrational energy to the materials in the co-ground.
The mill is composed of a cylindrical chamber in stainless steel with a polyurethane covering. Small highly packed grinding media made from a very hard material are placed inside the chamber.
The choice of the size and material of the grinding media depends on the properties of the material to be processed and the desired characteristics of the finished product.
The variation in some operating parameters results in a different energy transfer from the mill to the mixture and thus in different final characteristics of the product.
The vibratory mechanism is made up of a special electric motor linked to two “out of balance” counterweights. This entire group of components, attached directly to the base of the grinding chamber, is suspended by high-tension steel springs in order that energy is directly imparted to the grinding media.
The vibration created by the movement of this system is defined according to two physics-related measures: frequency and amplitude. The particularity lies in the fact that the vibration is of a tri-dimensional type, in that it is characterized by a horizontal as well as a vertical component. The former can be modified by changing the grinding angle i.e. by varying the position of one of the two counterweights.
In this way a different load movement is attained, and in addition the ener
Dees Jose′ G.
George Konata M.
Honig Milton L.
Unilever Home & Personal Care USA a division of Conopco, Inc.
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