Drug – bio-affecting and body treating compositions – Anti-perspirants or perspiration deodorants
Reexamination Certificate
2002-10-23
2004-12-28
Dodson, Shelley A. (Department: 1616)
Drug, bio-affecting and body treating compositions
Anti-perspirants or perspiration deodorants
C424S066000, C424S068000, C424S400000, C424S401000
Reexamination Certificate
active
06835374
ABSTRACT:
This invention relates to efficacious antiperspirant characterized by a property that renders invisible or transparent residue which remains on the skin. More particularly, the invention provides a highly efficacious concentrated antiperspirant system which when formulated into a conventional antiperspirant formulation and applied to the skin does not give unsightly white residue on the skin and clothing. The reduced residue effect of the antiperspirant product may be in the form of a stick, soft solid, suspension, roll-ons or spray, etc. The reduced residue or low residue means the product on application to the skin provides no discernible whiteness or visible residue.
BACKGROUND OF INVENTION
The antiperspirant and deodorant market offers a wide diversity of products. The physical forms of antiperspirants vary greatly. They include aerosols, pump sprays, squeeze sprays, creams, roll-ons, suspension roll-ons, deodorant sticks, clear gels, soft solids, etc. First and foremost in the hierarchy of consumer needs is long lasting control of odor and wetness. Consumers also want their antiperspirants to have excellent sensory properties on application and certain aesthetics. The preferred form of antiperspirant in USA is the stick application due to their high efficacy and good application properties.
Antiperspirants (except aerosols and sprays) are applied to an area of the body such as the axilla by rubbing to deposit a layer of antiperspirant. Accordingly, it is desirable that the ingredients used in any antiperspirant formulation result in an antiperspirant which is smooth, non-greasy, feel warm, quick drying, non tacky and leaves no visible residue. One of the disadvantages that exist with many stick formulations is that a white chalky residue is often left on the body and transferred to clothing. Since the use of dark-colored garments has increased among consumers, women in particular are dissatisfied with white residue from personal care products including antiperspirant and deodorant on clothing. A chalky residue after use of an antiperspirant stick is due in part to the fact that relatively large particles of the antiperspirant salt are employed in stick antiperspirants. Since the antiperspirant stick is white the deposit on the skin is also white.
In the early 1990's, clear products swept the consumer market place bringing everything from transparent dishwashing liquid to colorless colas. Although the popularity of these products has faded in some segments, product clarity remains a market force in the personal care industry. No where is a transparent product more sought after than in the antiperspirant stick market where consumers associate clarity with the lack of unsightly white residue on skin and clothing. This desire has prompted manufacturers of antiperspirant and deodorants to develop clear products. There are several apparent benefits associated with clear antiperspirant products. A clear product conveys a clean, pure and natural image; i.e., in an antiperspirant no visible product residue is left on skin or clothing. Consumer research rates clear products high on perception of superiority. The technology associated with clear stick and clear gel is specific and restricts the type of an antiperspirant active that can be used. Some of the important requirements for each of various antiperspirant forms are described below:
With respect to Clear Stick Antiperspirants:
The antiperspirant active must be stable in soluble and transparent form in the solvent system used; the solvent can be the same as that used to form the basic matrix for the gelling agent, or an alternative solvent.
An antiperspirant active that has already been pre-solubilised in a polyhydric alcohol, such as propylene glycol. This pre-solubilization ensures the formation of crystal clear compositions even in mixed glycol systems.
Use of enhanced efficacy aluminum zirconium actives is preferred to improve efficacy since the levels of use of the antiperspirant actives in clear sticks are markedly lower than in conventional solids. The comparative values are about 10-15% active level in clear sticks versus about 20-25% active level in opaque or translucent antiperspirant sticks.
Use of buffers to stabilize Di-benzaldehyde Monosorbitol Acetate (DBMSA) gelling agent or self buffered actives with higher pH than conventional antiperspirant actives.
The potential disadvantages with clear antiperspirant sticks include:
These products exhibit different application properties, particularly some stickiness after application and a less dry feel on the skin.
There is a potential for greater skin irritation due to the relatively high levels of glycolic fluids currently employed.
Clarity depends on the implementation and control of very precise manufacturing procedures at relatively high process temperatures and pHs. Also, antiperspirant salts themselves are weak oxidising agents, and under certain processing conditions may cause some degradation of glycols.
Shelf life stability frequently becomes difficult with clear sticks, and when they are unstable it becomes especially evident to the consumer. Unlike opaque products, clear sticks that begin to separate or cloud constitute a distinct and immediate turn-off for the consumer.
Lower clinical efficacy is generally acknowledged for this form of product, although they do conform to the Monograph requirement of a 20% sweat reduction in at least 50% of the test subjects. Lower efficacy is attributed to lower concentration of the active and higher pH of the active.
With respect to Clear Gel Antiperspirants:
Clear gel antiperspirant products offer several advantages. To illustrate, there is no product residue during or after application and a water-white clarity is achievable. High levels of enhanced efficacy actives can be used to deliver the expected levels of wetness protection. This is also a decided advantage compared to clear stick products.
There are several possible approaches to develop transparent formulations, such as the formation of gelled or thickened solutions, or the formation of micro-emulsions containing relatively high surfactant concentrations. Both of these approaches possess ingredient and production limitations.
A relatively simple and versatile third option is to form a water-in-oil emulsion in which the refractive indices of the continuous and dispersed phases are matched. This requires a precise control of the refractive index. The addition of a silicone surfactant such as dimethicone copolyol is desirable to achieve stability. Many formulations use a pre-blended combination of volatile silicone and dimethicone copolyol, also known as ‘self-emulsifying volatile silicone’, for ease of formulation.
Technically speaking, these emulsions are not microemulsions. The continuous or oil phase is typically a blend of liquids, and can include, for example, additives, such as, cyclomethicone, dimethicone, mineral oils, and various esters, as well as the silicone emulsifier.
The disperse or water phase typically includes one, or a combination of various polar species such as water, propylene glycol, sorbitol, glycerin, and ethanol, as well as the antiperspirant active.
To provide an optically clear gel, the refractive indices of the oil and water phase are adjusted as necessary to bring them within 0.0004 to 0.001 units at room temperature. Thus, the precise control of refractive index of an active and both the continuous and disperse phases is extremely important for this technology. Drawbacks to clear gels are that they suffer from becoming hazy when temperature changes or due to the evaporation of volatile ingredients like alcohol/silicone, causes an imbalance in the formulation. Efficacy of clear gel is also not as high as for opaque sticks and soft solids.
Reduced Residue Sticks
A solution to the consumer demand for an efficacious product with no residue is an opaque white stick with reduced residue or no residue. A number of patents have been issued for reduced residue sticks. However, there is a need for an active which when formulated into a so
Amin Pradip T.
Parekh Jawahar C.
Dodson Shelley A.
Plantamura Arthur J.
Reheis Inc.
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