Popular sunscreen seeks U.S. approval

Sep 01, 2004, 4:00am

National report - Mexoryl - a highly effective UVA sunscreen long used outside the United States - is now in the application process for approval by the U.S. Food and Drug Administration (FDA).

Although patent-holder L'Oréal remains tight-lipped about its product, mexoryl's reputation has preceded it: Some U.S. dermatologists tout it as the best UVA screen available today.

Darrell S. Rigel, M.D., former president of the American Academy of Dermatology and a practitioner in New York City, calls mexoryl a "great product."

Neil Swanson, M.D., chairman of dermatology at Oregon Health Sciences University in Portland, Ore., concurs. "Concentration for concentration," he says, "it's one of the best ingredients available."

But L'Oréal has offered little in the way of hard data to substantiate such assessments. Furthermore, the company refuses to discuss either FDA clinical trials or its U.S. marketing plans. This leaves mexoryl cloaked in an air of mystery that's unusual - especially for such a product as a sunscreen ingredient.

Fact from fiction Paris-based L'Oréal began marketing its first mexoryl-containing sunscreen in Europe about 10 years ago. Today, various formulations are available in the European Union, Canada, Asia, Mexico, South America and Australia. In Canada, Ombrelle Extreme uses mexoryl SX in combination with octocrylene, avobenzone (Parsol 1789, Givaudan-Roure) and titanium dioxide. In Europe and South America, Anthelios XL (sold under the La Roche-Posay label) contains mexoryl SX and XL, plus avobenzone, titanium dioxide and octocrylene. Two new formulas with an "Extra Fluid" texture also incorporate Tinosorb S (Ciba Specialty Chemicals).

Product literature describes Anthelios XL as non-oily, non-comedogenic, easy to apply, and having the highest UVA protection ever made. It also reports a UVA protection factor of 80 with the immediate pigment darkening test and a rating of 28 with the persistent pigment darkening test.

Emphasizing that her comments apply to countries and markets outside of the United States, Maeve Coburn, general manager of U.S. operations for the La Roche-Posay Division of L'Oréal, describes the combination of avobenzone and mexoryl as "the most effective protection against UVA/UVB radiation known today."

She also notes, "We do not plan to license mexoryl to other companies. We have a fortune invested in R&D."

More on mexoryl UVA has been implicated as a disease factor in skin cancer, polymorphous light eruptions (PMLE), lupus, solar urticaria, hydroa vacciniforme, porphyria and chronic actinic dermatitis. It's also linked to photoaging indicators such as sagging skin, decreased elastic fibers and an increase in elastosis.

In the 1980's, L'Oréal began looking for a UVA filter to cover the 320-nm to 400-nm range. It also sought a filter that was soluble, effective, photostable, absorbent, easy to formulate, thermostable, odorless, non-staining, safe and moderately priced. After synthesizing hundreds of molecules, L'Oréalselected mexoryl SX (terephthalylidene dicamphor sulfonic acid), which the company says is nearly impervious to solar radiation, as its core solution. The newer mexoryl XL (drometrizole trisiloxane) reinforces and extends the protection offered by SX, company officials say.

According to Dominique Moyal, Ph.D., in charge of evaluating sunscreen efficacy for L'Oréal, the former is a hydrophilic filter with a maximum absorption at 345 nm, while the latter is a lipophilic filter with two maxima: the first in UVB at 303 nm and the second in UVA at 344 nm.