ingridients:
Active Ingredients: (w/w)
octyl methoxycinnamate 7.4% (Octinoxate)
, butyl methoxydibenzoylmethane 3% (avobenzone), oxybenzone 2%
These filters are not perfect. They give weak UVA protection.
According to this site:
http://www.biochemiaurody.com/English/EUfilters.htm
Octinoxate serves as UVB protection.
Oxybenzone blocks some UVA rays but not all of them (information in the article below).
Avobenzone (Parsol) raised many question about its photostability.
here is a site that is not scientific at all but the discussion can give you some ideas about why these filters are not stable:
http://forums.vogue.com.au/archive/i...p/t-88879.html
here is the article which is talking about why the filters available in the US are inferior to those available in Europe, Canada:
http://pubs.acs.org/cen/coverstory/8...unscreens.html
an exert from this article:
Seven UV filters listed in the U.S. monograph block UV-A rays, Shaath says. But
oxybenzone, for instance, is primarily a UV-B filter that also blocks some UV-A rays. Menthyl anthranilate is not a broad-spectrum UV-A filter.
Avobenzone provides broad-spectrum UV-A blockage but quickly loses potency on the skin if not formulated properly. Sulisobenzone and dioxybenzone are difficult to solubilize and are rarely used. Two physical blockers, titanium dioxide and zinc oxide, are difficult to incorporate into formulations.
here is the list of the sunscreens containing superior filters:
http://www.biochemiaurody.com/Englis...sunscreens.htm
I heard that Parsol is more stable when it is combined with some stabilizers, for example Octocrylene is supposed to make Parsol more stable (such combination can be find in Cetaphil moisturizer, for example.)
"Octocrylene is a weak but stable UVB absorber used to protect other agents from degrading.
Avobenzone (Parsol-1789) is a benzophenone with fair UVA protection, but it degrades readily and tends to be irritating."
Source:
http://www.shorelaser.com/Cosmeceuticals.html
from what I can see, Superdefense dosn't contain any stabilizing agents.
another exert:
Parsol 1789, otherwise known as avobenzone, is a dibenzoylmethane. It is a true UVA absorber. A problem with avobenzones has been an in vitro loss of photostability.7 Some preparations reportedly lose more than a third of their activity after an hour of sun exposure. Newer preparations combine Parsol with stabilizing agents. For example, Ombrelle uses Octocrylene plus Parsol 1789 to augment photostability.
source:
http://www.hmpcommunications.com/SA/...00107f3&type=A
Im sorry for giving you so many different sources, but its hard to find all these information in one article
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