Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
1999-12-10
2001-09-25
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
06294156
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to topically applied sunscreen compositions. In particular, the invention relates to sunscreen compositions containing sunscreen agents that provide an enhanced amount of photoprotection by means of being in combination with submicron fluororesin particles. The sunscreen compositions feel better on the skin and are less irritating than typical sunscreens because the enhanced photoprotection is not achieved by using greater quantities of the sunscreen agent.
BACKGROUND OF THE INVENTION
Sunscreen compositions are frequently used to protect skin that is exposed to the sun for a variety of reasons such as sun bathing, or spending leisure time or working out of doors. Topical sunscreen compositions, which are easily applied to the skin, are usually in the form of a lotion, oil, cream or emulsion (water-in-oil and oil-in-water). Sunscreen compositions contain sunscreen agents to protect the skin from the harmful UV rays of the sun. These rays are generally in the form of UV-A and UV-B radiation which range from about 290 to 400 nm in wavelength.
There are short and long term hazards associated with prolonged exposure to UV radiation. Some of the long term effects include malignant changes in the skin surface, premature aging of the skin as evidenced by wrinkles, yellowing, cracking, telangiectasis (spider vessels), solar keratoses (growths), ecchymoses (subcutaneous hemorrhagic lesions), and loss of elasticity (sagging). A major short term effect of prolonged exposure to UV light is erythema, commonly known as a sunburn.
The amount of photoprotection against erythema is the basis for the determination of the SPF (“sun protection factor”) value. The SPF value measures the amount of protection from the sun provided before a certain level of erythema is experienced. Compositions having higher SPF values are preferred because they offer more protection against the harmful effects caused by the sun and UV radiation.
Sunscreen agents act by absorbing, scattering or blocking UV radiation and thus, prevent UV radiation from penetrating the skin. They are available as both organic and inorganic agents. Typical organic agents include. for example. PABAs (p-aminobenzoic acids), benzophenones. salicylate esters and dioxybenzone. Examples of inorganic agents include zinc oxide, titanium dioxide and calamine. To achieve higher SPF values, typically, greater quantities of the sunscreen agent or combination of sunscreen agents are added to the composition. However, greater quantities of sunscreen agents present certain challenges in formulation, especially with respect to stability. For example, titanium dioxide tends to agglomerate and become less effective as a sunscreen agent. It is also a frequent complaint that sunscreens containing particularly high concentrations of titanium dioxide have an unpleasant or grimy feel on the skin and result in a white or blue hue on the skin. Other negative qualities that result from using high concentrations of inorganic sunscreen agents are the opaqueness of the formula when a clear formula is desired. the change in color of the formula, or other adverse aesthetic effects.
Producing a topical sunscreen composition with a high SPF is difficult to achieve without the negative characteristics associated with using larger quantities of sunscreen agents. Efforts to “boost” the SPF value of a sunscreen composition are demonstrated in U.S. Pat. Nos. 5,468,471 and 5,573,754. However, they include components in addition to the sunscreen agent that are relatively costly and not easily manufactured. Thus, there is a continued effort to find ways of boosting the SPF of topical sunscreen compositions. It is, therefore, an object of the present invention to reduce the irritation potential of topical sunscreen compositions to levels which will be acceptable to the average user of the product and to provide a topical sunscreen composition that is appealing to the consumer.
SUMMARY OF THE INVENTION
The present invention relates to a sunscreen composition that has a photoprotective effect enhanced by the combination of a fluororesin polymer of a submicron particle size and a sunscreen agent in a hydrophobic vehicle. The composition enhances the photoprotective effect of the composition without causing adverse skin reactions or being aesthetically unpleasant to the user. An enhancement of the photoprotective effect can be demonstrated, for example, by an increase in SPF by 2 or 3 units. The increase is achieved primarily without adding larger quantities of the sunscreen agent. The invention also relates to a cosmetic or pharmaceutical composition comprising the combination, as well as a method of boosting the SPF value of a sunscreen and methods for reducing the irritancy experienced on the skin and providing photoprotection to the skin by applying to the skin the compositions of the present invention.
The invention is particularly usefull in the preparation of formulations containing octyl methoxycinnamate and benzophenone as well as other organic sunscreen agents because the SPF is increased without adding larger quantities of these organic sunscreen agents or other inorganic sunscreens. Therefore, the stability and aesthetic challenges experienced with larger quantities of organic and inorganic sunscreen agents can be avoided. The compositions and methods of the present invention feel comfortable on the skin, look more appealing and achieve an increased SPF value.
DETAILED DESCRIPTION OF THE INVENTION
It has now been unexpectedly discovered that the SPF value of a sunscreen composition can be increased when a fluororesin polymer having a submicron particle size is combined with a sunscreen agent. The fluororesin polymer of the present invention has been previously used in cosmetic products as described in Japanese Publication Nos. 06-135820, 05-163114, 02-088512, and U.S. Pat. No. 5,093,110, the contents of which are herein incorporated by reference. Fluororesins have been previously described for use in sunscreen compositions. as for example, in Japanese Application Disclosure Nos. 60-149515, 05-339139. However, the use of fluororesins in sunscreens has been in an arrangement where the sunscreen agent surrounds the fluororesin (i.e., the fluororesin is “coated” by the sunscreen) or is bonded to the fluororesin by a chemical reaction. In the present invention the advantages of combining the sunscreen agent with the submicron fluororesin in a composition are described and found to surprisingly boost SPF and reduce irritation on the skin. These benefits and characteristics have not previously been disclosed.
It has been discovered that a certain particle size range of known fluororesins are capable of enhancing the SPF of sunscreen agents. The submicron size of the fluororesin particles effects the ability of fluororesin to achieve, when combined with the sunscreen agent, a boost in the SPF value of the sunscreen composition. The particle size ranges from about 200 nm to about 1200 nm. preferably between about 400 to about 800 nm, and more preferably about 600 nm. The fluororesin can be made by any method known in the art. Methodology for production of submicron fluororesin, for example, is disclosed in U.S. Pat. No. 4,052,278, the contents of which are incorporated herein by reference. While not wishing to be bound by any particular theory, it is believed that the efficacy of these sunscreen compositions in substantially increasing the SPF value of the composition is related to the optical properties of the submicron sized fluororesin particles, which synergistically along with the sunscreen agent prevent the harmful rays of the sun from damaging the skin.
The fluororesins can be any fluorinated polymer which is well known for having low friction properties and for being used as a dry lubricant powder. Preferably, the fluororesin is polytetrafluorethylene (“PTFE”), commonly known as Teflon and available from E.I. Du Pont de Nemours and Company. The fluororesin is a polymer and has a degree of polymerization greater than 20
Dwyer Rosa M
Lentini Peter J.
Color Access Inc.
Dodson Shelley A.
Kenyon & Kenyon
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