Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
2000-02-23
2001-05-01
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
06224854
ABSTRACT:
TECHNICAL FIELD
The present invention relates to compositions suitable for providing protection against the harmful effects of ultraviolet radiation having excellent efficiency, broad spectrum UV efficacy, and photostability. The compositions comprise a UVA-absorbing dibenzoylmethane sunscreen active, a styrene derivative and a suitable carrier.
BACKGROUND OF THE INVENTION
It is well known that exposure to sunlight can pose a number of hazards to the skin. These damaging effects may result not only from sunbathing but also from the sunlight exposure associated with daily outdoor activities. The major short term hazard of prolonged exposure to sunlight is erythema, i.e., sunburn, which primarily results from UVB radiation having a wavelength of from about 290 nm to about 320 nm. Over the long term, however, malignant changes in the skin surface often occur. Numerous epideminologic studies demonstrate a strong relationship between sunlight exposure and human skin cancer. Another long term hazard of ultraviolet radiation is premature aging of the skin, which is primarily caused by UVA radiation having a wavelength of from about 320 nm to about 400 nm. This condition is characterized by wrinkling and pigment changes of the skin, along with other physical changes such as cracking, telangiectasis, solar dermatoses, ecchymoses, and loss of elasticity. The adverse effects associated with exposure to UV radiation are more fully discussed in DeSimone, “Sunscreen and Suntan Products,”
Handbook of Nonprescription Drugs
, 7th Ed., Chapter 26, pp. 499-511 (American Pharmaceutical Association, Washington, D.C.; 1982); Grove and Forbes, “A Method for Evaluating the Photoprotection Action of Sunscreen Agents Against UV-A Radiation,”
International Journal of Cosmetic Science
, 4, pp. 15-24 (1982); and U.S. Pat. No. 4,387,089, DePolo, issued Jun. 7, 1983.
As a result of the abovementioned hazards associated with sunlight exposure, the general public's interest in the sun protection product market has grown considerably. Today, there are not only sunscreen products for sunbathing but there are also a variety of personal care products containing sunscreens, particularly cosmetic type products which are worn daily. “Personal care products” refer to health and cosmetic beauty aid products generally recognized as being formulated for beautifying and grooming the skin and hair. For example, personal care products include sunscreen products (e.g., lotions, skin creams, etc.), cosmetics, toiletries, and over-the-counter pharmaceutical products intended for topical usage.
Many conventional sunscreen products, in particular, are deficient, however, due to their inability to provide efficacious protection against broad spectrum UV radiation, i.e., protection against both UVB and UVA radiation. Today, most commercially available sunscreen products are efficient at absorbing UV radiation in the 290 nm to 320 nm UVB region such that sunburn of the skin is prevented. They are less efficient when it comes to absorbing light which falls in the 320 nm to 400 nm UVA region, which leaves the skin vulnerable to premature skin aging. This deficiency is due in part to the limited number of UVA absorbing sunscreen actives which are both commercially available and approved for global use. One class of these sunscreen actives includes dibenzoylmethane compounds which provide broad spectrum UV protection and 4-tert-butyl-4′-methoxydibenzoylmethane, in particular, is also approved for global use. Unfortunately, these sunscreens tend to photodegrade upon exposure to UV radiation thereby reducing their UVA efficacy. Consequently, sunscreen products which include these compounds are typically more difficult to formulate due to the inherent lack of photostability of dibenzoylmethane compounds. One approach to stabilize these types of sunscreens is described in U.S. Ser. No. 07/929,612, Deckner, filed Aug. 13, 1992, involving the use of benzylidene camphor sunscreens to stabilize the dibenzoylmethane compound. Such compositions, however, are not currently approved for global use on humans.
Thus, there is a need for photostabilized compositions suitable for providing protection against the harmful effects of UV radiation to human skin. In particular, in the personal care industry, a need remains for sunscreen products having excellent photostability, efficiency, and which provide broad spectrum UV protection (i.e., against both UVA and UVB radiation) in a safe and economical manner.
Likewise, in other industries such as the automotive care, marine vehicle care, household care, animal care, and coatings industries, UV radiation causes undesirable wear and damage. Therefore, a need exists for photostabilized compositions suitable for providing protection against the harmful effects of UV radiation to a variety of objects and/or materials prone to sun exposure.
It has surprisingly now been found that the compositions of the present invention, which comprise a UVA-absorbing dibenzoylmethane sunscreen active, a styrene derivative, and a suitable carrier, provide excellent photostability, efficiency, and UV protection efficacy (including both UVA and UVB protection), in a safe and economical manner.
SUMMARY OF THE INVENTION
The present invention relates to a composition suitable for providing protection against the harmful effects of ultraviolet radiation comprising:
a) an effective amount of a UVA-absorbing dibenzoylmethane sunscreen active;
b) an effective amount of a styrene derivative having the formula
wherein at least one of R
1
, R
2
, and R
3
is an electron-withdrawing substituent, provided that R
1
is other than an aryl or a methyl, that R
2
and R
3
are each other than a ketone, and that R
2
and R
3
together do not form a camphor group; wherein the remaining substituents of R
1
, R
2
, and R
3
that are not electron-withdrawing substituents are selected from the group consisting of H and electron-donating substituents; and wherein R
4
is selected from the group consisting of H, electron-donating substituents other than ethers, and electron-withdrawing substituents other than cyanos; and
c) a suitable carrier.
In preferred embodiments, the UVA-absorbing dibenzoylmethane sunscreen active and the styrene derivative are present in “safe and effective” amounts and the mole ratio of the UVA-absorbing dibenzoylmethane sunscreen active to the styrene derivative is from about 8:1 to about 1:1, more preferably from about 4:1 to about 1:1, and most preferably from about 2:1 to about 1:1. The present invention also relates to methods for providing protection to skin from the harmful effects of UV radiation by topical application of such compositions. Furthermore, the present invention relates to methods of stabilizing a UVA-absorbing dibenzoylmethane sunscreen active.
DETAILED DESCRIPTION OF THE INVENTION
The compositions of the present invention are useful for providing protection against the harmful effects of ultraviolet radiation, especially to human skin. The essential components of these compositions are described below. Also included is a nonexclusive description of various optional and preferred components useful in embodiments of the present invention.
The present invention can comprise, consist of, or consist essentially of any of the required or optional ingredients and/or limitations described herein.
All percentages and ratios are calculated on a weight basis unless otherwise indicated. All percentages are calculated based upon the total composition unless otherwise indicated.
All molar weights are weight average molecular weights and are given in units of grams per mole.
All ingredient levels are in reference to the active level of that ingredient, and are exclusive of solvents, by-products, or other impurities that may be present in commercially available sources, unless otherwise indicated.
All measurements made are at ambient room temperature, which is approximately 73° F., unless otherwise designated.
All documents referred to herein, including patents, patent applications, and printed public
Dodson Shelley A.
Hilton Michael E.
Kendall Dara M.
The Procter & Gamble & Company
Tsuenki Fumiko
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