Ecamsule

Ecamsule (USAN, trade name Mexoryl® SX, INCI Terephthalylidene Dicamphor Sulfonic Acid) is a chemical which is added to many sunscreens to filter out UVA rays. It is a benzylidene camphor derivative, many of which are known for their excellent photostability.^[1]

Although there are a few different UV absorbers with the trade name Mexoryl, only two of them are widely used where approved. Mexoryl SX (water soluble) and Mexoryl XL (INCI Drometrizole Trisiloxane, oil soluble). Together they show a synergistic effect in protection.^[2] The patents are held by L’Oréal. Sunscreens containing ecamsule are exclusive to L’Oréal and its brands.

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Mode of action

Exposed to UV, ecamsule undergoes reversible photoisomerization, followed by photoexcitation. The absorbed UV is then released as thermal energy, without penetrating the skin.

UVB rays cause short-term sunburn and skin cancer; UVA rays cause wrinkling and may have some role in development of skin cancer. There is no official rating for UVA protection in the US. In Europe, there are several different rating systems that are used to measure effectiveness in blocking UVA rays, including the IPD (immediate pigment darkening assay) and the PPD (persistent pigment darkening assay). The UVB range is 280 to 320 nanometers, and the UVA range is 320 to 400. Ecamsule protects against UV wavelengths in the 290–400 nanometer range, with peak protection at 345 nm.^[3][4] Since ecamsule doesn't cover the entire UV spectrum, it should be combined with other active sunscreen agents to ensure broad-spectrum UV protection. Ecamsule is a photostable organic UVA absorber, meaning it doesn't degrade significantly when exposed to light. This is in contrast to the widely used UVA absorber avobenzone that is not intrinsically photostable and requires photostabilizers to prevent significant degradation in light.^[5][6][7]

Efficacy

A 5% ecamsule containing sunscreen can prevent early changes leading to photoaging in humans. A broad spectrum sunscreen with ecamsule, avobenzone and octocrylene significantly reduces the skin damage associated with UV exposure in human subjects.^[8]

In studies done in mice it reduces the formation of UV induced pyrimidine dimers and delays the onset of skin cancer. In vitro ecamsule effectively protects against the harmful effects of UV.^[9]

Safety

Ecamsule has little percutaneous absorption and little systemic effects, therefore it is considered relatively safe.^[10] A mouse study shows that it does not increase the probability of promoting skin cancer.^[11] Studies done in vitro show that it is not photomutagenic.^[12]

Because ecamsule is an acid it needs to be neutralized in order to be used without offsetting the final pH of the sunscreen too much. Usually this is done with triethanolamine.

Availability

L’Oréal patented ecamsule first in 1982. It was approved in the EU in 1991. Sunscreens based on ecamsule have been available in Europe, Canada and other parts of the world since 1993, and was just recently given approval by the FDA in the U.S.^[13] However this approval only extends to ecamsule containing sunscreens registered under a New Drug Application, not ecamsule itself.^[14][15]

See also

• Avobenzone
• Sunburn
• Ultraviolet

References

1. ^ Deflandre A, Lang G (Apr 1988). "Photostability assessment of sunscreens. Benzylidene camphor and dibenzoylmethane derivatives". Int J Cosmet Sci 10(2): 53-62.
2. ^ Moyal D. (Oct 2004). "Prevention of ultraviolet-induced skin pigmentation". Photodermatol Photoimmunol Photomed 20(5): 243-7. PMID 15379874.
3. ^ Fourtanier A, Labat-Robert J, Kern P, Berrebi C, Gracia AM, Boyer B. (Apr 1992). "In vivo evaluation of photoprotection against chronic ultraviolet-A irradiation by a new sunscreen Mexoryl SX.". Photochem Photobiol 55(4): 549-60. PMID 1320278.
4. ^ Seite S, Moyal D, Richard S, de Rigal J, Leveque JL, Hourseau C, Fourtanier A. (Jun 1998). "Mexoryl SX: a broad absorption UVA filter protects human skin from the effects of repeated suberythemal doses of UVA.". J Photochem Photobiol B. 44(1): 69-76. PMID 9745729.
5. ^ Chatelain E, Gabard B. (Sep 2001). "Photostabilization of Butyl methoxydibenzoylmethane (Avobenzone) and Ethylhexyl methoxycinnamate by Bis-ethylhexyloxyphenol methoxyphenyl triazine (Tinosorb S), a new UV broadband filter". Photochem Photobiol 74(3): 401-6. PMID 11594052.
6. ^ Tarras-Wahlberg N, Stenhagen G, Larko O, Rosen A, Wennberg AM, Wennerstrom O (Oct 1999). "Changes in ultraviolet absorption of sunscreens after ultraviolet irradiation". J Invest Dermatol 113(4): 547-53. PMID 10504439.
7. ^ Wetz F, Routaboul C, Denis A, Rico-Lattes I (Mar-Apr 2005). "A new long-chain UV absorber derived from 4-tert-butyl-4'-methoxydibenzoylmethane: absorbance stability under solar irradiation". J Cosmet Sci 56(2): 135-48. PMID 15870853.
8. ^ Seité S, Colige A, Piquemal-Vivenot P, Montastier C, Fourtanier A, Lapière C, Nusgens B (Aug 2000). "A full-UV spectrum absorbing daily use cream protects human skin against biological changes occurring in photoaging". Photodermatol Photoimmunol Photomed 16(4): 147-55. PMID 11019938.
9. ^ Marrot L, Belaidi JP, Chaubo C, Meunier JR, Perez P, Agapakis-Causse C (Sep 1998). "An in vitro strategy to evaluate the phototoxicity of solar UV at the molecular and cellular level: application to photoprotection assessment". Eur J Dermatol 8(6): 403-12. PMID 9729050.
10. ^ Benech-Kieffer F, Meuling WJ, Leclerc C, Roza L, Leclaire J, Nohynek G (Nov-Dec 2003). "Percutaneous absorption of Mexoryl SX in human volunteers: comparison with in vitro data". Skin Pharmacol Appl Skin Physiol 16(6): 343-55. PMID 14528058.
11. ^ Fourtanier A (Oct 1996). "Mexoryl SX protects against solar-simulated UVR-induced photocarcinogenesis in mice". Photochem Photobiol 64(4): 688-93. PMID 8863475.
12. ^ Dean SW, Dunmore RH, Ruddock SP, Dean JC, Martin CN, Kirkland DJ (May 1992). "Development of assays for the detection of photomutagenicity of chemicals during exposure to UV light. II. Results of testing three sunscreen ingredients". Mutagenesis 7(3): 179-82. PMID 1602971.
13. ^ Long-awaited sunscreen approved for sale in U.S.. USA Today (July 24, 2006).
14. ^ http://www.cosmeticsdesign.com/news/ng.asp?id=69386-l-oreal-mexoryl-sunscreen-uva
15. ^ http://www.cosmeticsandtoiletries.com/articles/4539726.html,