Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
2000-04-18
2001-05-15
Dodson, Shelley A. (Department: 1616)
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
C424S060000, C424S400000, C424S401000
Reexamination Certificate
active
06231837
ABSTRACT:
FIELD OF THE INVENTION
The present invention is in the broader technical field relating to compositions for the topical application of active agents to the skin with sufficient penetration to be efficacious. Such active agents can be cosmetic agents or therapeutic agents; thus, the disciplines of pharmacology and cosmetology are involved. The present invention is, further, in the narrower technical field relating to cosmetic compositions where the active agent is a sunless tanning compound, in particular dihydroxyacetone, which is delivered by topical application of a cosmetic product formulation containing dihydroxyacetone to the skin of a user of said product. In this narrower technical field, it is appreciated that desirable product formulations have sufficient stability and skin penetration to provide an even tan of the desired color in a timely fashion.
BACKGROUND OF THE INVENTION
The prevailing cultural esthetic among fair-skinned persons in many countries and places is to have a skin which is tanned, i.e., which has a light yellowish brown or even deeper brown color produced by exposure to the sun or to an artificial source of ultraviolet light. The tanning of the skin is produced as a result of the darkening of preformed melanin, accelerated formation of new melanin, and retention of melanin in the epidermis as a result of retardation of keratinization. The darkening of existing melanin, possibly caused by oxidation and referred to as the Meirowsky phenomenon, begins within a few seconds of exposure to long-wave ultraviolet light and is complete within minutes up to a few hours, depending on the individual involved.
For those many individuals who wish to achieve a tanned skin, the most readily available means for doing so is by exposure of their skin to natural sunlight. However, this method carries with it certain hazards, chief among which is the risk of sunburn, i.e., actual injury to the skin produced by excessive exposure to ultraviolet rays. The injury is accompanied by erythema, tenderness, and sometimes blistering. Furthermore, excessive exposure to ultraviolet radiation is considered by the medical community to be a leading factor in the oncogenesis of melanomas and other skin cancers, as well as an accelerating agent in the aging of the skin, particularly its tendency to sag and wrinkle. In order to mitigate or prevent such excessive exposure, such individuals will usually seek the protection of various sunscreen products, which contain sunscreen agents that act either by absorbing the ultraviolet radiation or by reflecting incident light. Sunscreen products also provide the user with other protections and benefits which are desirable, such as those available from skin moisturizing, protective and healing compounds, anesthetic and anti-inflammatory agents, etc. Certain embodiments of the present invention utilize such conventional sunscreen materials in order to achieve a product with the most universal appeal and with the greatest possible number of benefits to its users.
Where ultraviolet radiation is the source of skin tanning, it should be noted briefly that such electromagnetic radiation lies beyond the violet end of the spectrum, whence its name. Ultraviolet radiation lies between violet rays and roentgen or “X” rays, is characterized by wavelengths between 200 and 400 nm, and has powerful actinic and chemical properties. Over 99% of ultraviolet radiation has wavelengths between 320 and 400, and is referred to as ultraviolet A, or simply UVA. The remaining 1% of ultraviolet radiation comprises ultraviolet B, or UVB radiation, which has wavelengths between 290 and 320 nm. UVB causes sunburn and a number of damaging photochemical changes within cells, including damage to DNA, leading to premature aging of the skin, premalignant and malignant changes, and a variety of photosensitivity reactions. Wavelengths between 200 and 290 nm characterize ultraviolet C radiation, or UVC, all of which is filtered out by the ozone layer and does not reach the earth's surface. Many persons, in order to achieve a satisfactorily tanned skin but unable to take advantage of naturally occurring sunlight, have resorted to the use of artificial sources of ultraviolet light, which are also much easier to regulate with respect to the amount of ultraviolet radiation to which the skin is exposed, than is the case with natural sunlight. On the other hand, there are many persons who, for a variety of reasons, make use of so-called self-tanning or sunless product formulations in order to achieve a satisfactory tan.
For example, many persons have skin complexions which do not tan readily or evenly when exposed to sunlight, and many others suffer significant adverse side effects from sun exposure, including severe sunburn. For such people, once a tan is obtained, there is a great deal of interest in maintaining or extending the life of that tan, which will naturally dissipate over time as the layers of skin which actually comprise the tan become necrotic and are eventually sloughed off. All such persons would greatly benefit from access to any means of obtaining a tanned skin, or at least a skin having the appearance of a naturally tanned skin, which did not require being exposed to sunlight, with all of the attendant adverse effects which arise from such exposure to ultraviolet radiation. Accordingly, such persons in ever greater numbers have turned to so-called self-tanning or sunless product formulations in order to achieve a “tan” without going through the harsh medium of the sun. However, there are many other persons who, although not as severely affected by exposure to ultraviolet radiation, also have turned to self-tanning products as a way of achieving a more uniform tan, of obtaining a deeper tan with significantly less total exposure to sunlight, and of extending the natural life of the tan which they have acquired for themselves. For such persons, a suitable product is to be found in those embodiments of the present invention which combine the components of a self-tanning composition with the components of a sunscreen formulation.
Self-tanning agents and formulations of various types and compositions are known in the art. For example, sunless tanning agents which have been discovered and used heretofore include dihydroxyacetone (DHA), glyceraldehyde (glycerol aldehyde) and related alcohol-aldehydes, various indoles and imidazoles and their derivatives, and pigmentation agents approved for use with humans, e.g., methoxsalen and trioxsalen. Dihydroxyacetone in particular is currently the self-tanning agent most widely used, and it has been known in the art for some time as an artificial tanning agent for use on the human epidermis. As used hereafter, the term “dihydroxyacetone” will be used to mean not only that specific composition of matter, but all of the other species described further herein which may be substituted for dihydroxyacetone in accordance with the objectives herein enumerated, whether with better or poorer results as measured by the several criteria also further below-described in more detail.
It has been widely postulated in the art that dihydroxyacetone achieves this effect by reacting with various skin proteins and amino acids to produce a tan-colored reaction product. Dihydroxyacetone has been used in a number of self-tanning formulations over the years combined, e.g., with colorants and sunscreen agents. Dihydroxyacetone, which may also be named as 1,3-dihydroxy-2-propanone, has the following structural formula:
which corresponds to a elementary formula of C
3
H
6
O
3
and a molecular weight of 90.08. Dihydroxyacetone is a crystalline powder which is fairly hygroscopic and has a melting point of about 75-80° C. It has a characteristic odor. The normal form in which dihydroxyacetone exists is a dimer, which is slowly soluble in 1 part water and 15 parts ethanol. However, when dihydroxyacetone is freshly prepared it reverts rapidly to the monomer form, which is very soluble in water, ethanol, ether and acetone.
As already mentioned, dihydroxyacetone is
Scott John A.
Stroud Eric M.
Dodson Shelley A.
Franks Robert A.
Schering-Plough Healthcare Products Inc.
LandOfFree
Self-tanning dihydroxyacetone formulations having improved... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Self-tanning dihydroxyacetone formulations having improved..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Self-tanning dihydroxyacetone formulations having improved... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2568546