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Wed Mar 14, 2007 1:49 am  |
ETHYLHEXYL METHOXYCINNAMATE is in Sofina SS and I was hoping whether anyone knoew if it is photostable?
Thank you.
Emma x |
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Wed Mar 14, 2007 2:00 am |
sorry if i worried you emma  I just know some people prefer not to use cinnamates. I think it depends on overall ingrediants too ie certain ingrediants should be in a sunscreen togethor to stabilise each other. Anyway i think all it means is that if you're continually in the sun then you should apply every 2 hrs to avoid any instability problems ie. free radical damage. But if you get minimal sun exposure it shouldnt break down so quickly. Dont take what i say as gospel though!
Sorry i cant remember where i read about cinnamates and photostability. Hopefully someone in the know will chime in  |
_________________
39, in Australia, using retin a, Skin actives I Bright and Antiaging Cream, change sunscreen regularly currently. |
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Wed Mar 14, 2007 2:18 am |
Hi Carol,
Please don't apologise - I'd much rather know things about a SS I'm using.
Emma x |
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Wed Mar 14, 2007 2:48 am |
I'm interested in this too because I only use Asian sunscreens which use this ingredient (for UVB protecton) plus zinc oxide (for UVA protection) for the sun protection. Here's what I found:
http://findarticles.com/p/articles/mi_qa3931/is_200109/ai_n8973109
"Since AVB (Avobenzene, Parasol) was shown to destabilize ethylhexyl methoxycinnamate (EHM)..."
http://www.kantonslabor-bs.ch/content.cfm?nav=17&content=23&Command=details&year=2004&kat=all&ID=70
In comparison, and to our surprise, EHMC (ethylhexyl methoxycinnamate), BMDM, IMC and MBC were broken down by up to 40%
So stable sunscreens accdg to this study:
PBSA, EHS, EHT, MBBT, BEMT, DEBT, OC and DTS
PBSA = Phenylbenzimidazole Sulfonic Acid
EHS = Ethylhexyl Salicylate
EHT = Ethylhexyl Triazone
BEMT = Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine
DEBT = Diethylhexyl Butamido Triazone
OC = Octocrylene
DTS = Drometrizole Trisiloxane
Unstable accdg to this study:
EHMC, BMDM, IMC and MBC
EHMC = Ethylhexyl Methoxycinnamate
BMDM = Butyl Methoxydibenzoylmethane
IMC = Isoamyl Methoxycinnamate
MBC = 4-Methylbenzylidene Camphor
"The decay of these four filters is strongly dependent on formulation (see table).
It is widely known that UV filters can be stabilised by using particular combinations.
The greatest decay was observed for a day cream containing one UV filter, EHMC.
The combination of several unstable filters led to the highest decay rate we have observed for a sunscreen."
Another study:
http://www.nature.com/jid/journal/v113/n4/full/5603262a.html
"The absorption spectra of the compounds were recorded before and after irradiation. The absorbance of 2-ethylhexyl 4-methoxycinnamate was reduced significantly, whereas 3-(4-methylbenzyliden)camphor seemed to be rather stable."
This article says that it is stabilized by another ingredient:
http://www.chemsoc.org/chembytes/ezine/2001/woodruff_jul01.htm
"However OMC (ethylhexyl methoxycinnamate) with 4-methylbenzylidene camphor is almost completely stable, even at high doses of radiation. This combination is frequently used in typical suncream formulations." |
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Wed Mar 14, 2007 3:22 am |
oops, want to make a quick note and I can't seem to edit. =\
I believe Asian sunscreens also contain Titanium dioxide and Zinc oxide, so since those are physical blocks, they should be stable, just the protection isn't as high as with chemical blocks I believe...(since they're not as concentrated as in purely physical sunscreens)
I read though that (a Korean sunscreen), Laneige SPF 50, PA+++ does have Tinosorb among other ingredients and supposedly has a PPD about 10, so it's decent. I've tried it, and of course the finish isn't as nice and elegant as Japanese sunscreens, but it may be worth a try if you want a nicer textured Asian sunscreen. |
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Wed Mar 14, 2007 8:47 am |
I just want to make two points here.
1. Zinc oxide and titanium dioxide are broad spectrum filters and also offer UVB protection so even if the EHMC is degraded the physical filters are also there offering some UVB protection.
2.I read something very interesting in the one link that maiea provided (the first link listed as findarticles) and it is something that I had never thought of before.
" In conclusion, commercial sunscreens containing the combination of AVB and EHM UV filters have been shown to be photolabile to various degrees. A common feature of these sunscreens is that they begin with SPF higher than that claimed on the label; however, as their exposure to sunlight increases the UV absorbance of these sunscreens decline. Since during SPF measurements in vivo, photochemical changes during exposure are automatically taken into account, one cannot differentiate between a constant SPF and a decreasing SPF over irradiation time."
It never dawned on me to look at it this way but the SPF on a sunscreen is not guessed or calculated it is actually determined by testing!! (At least in the US. Although I am guessing that Europe and Japan also would do this.) I don't know the specifics of the testing as in how long the test is carried out or exactly how it is done. I get the impression from the above quote that they have to take into account the fact that certain sunscreeen ingredients do degrade and that they need to adjust the amount in the formula to get a certain SPF under test conditions. Very interesting!!! |
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