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Dermatol Surg. 2008 Nov;34(11):1469-76. doi: 10.1111/j.1524-4725.2008.34311.x. Epub 2008 Sep 15.

Protection afforded by sunscreens containing inorganic sunscreening agents against blue light sensitivity induced by aminolevulinic acid.

Author information

1
Innovaderm Research Inc, Montreal, QC, Canada. rbissonnette@innovaderm.ca

Abstract

BACKGROUND:

Application of aminolevulinic acid (ALA) for photodynamic therapy induces significant sensitivity to visible light.

OBJECTIVE:

To determine whether sunscreens containing inorganic agents are effective against sensitivity to blue light induced by ALA application.

METHODS & MATERIALS:

Twenty subjects received application of ALA on the arm. Thirty minutes before blue light exposure, two sun protection factor 50 inorganic-based sunscreens containing iron oxide 3.2% and 0.2% were applied on separate areas where ALA was applied; a third area received no sunscreen. Small areas of skin were exposed to increasing fluences of blue light 3 or 18 hours later, and the minimal phototoxic dose (MPD) was noted.

RESULTS:

Three hours after ALA application MPD was 29.2 and 22.6 J/cm(2) for skin protected with sunscreen containing iron oxide 3.2% and 0.2%, respectively, and 10.6 J/cm(2) for unprotected skin (p=.003 and .0497 respectively). At 18 hours after ALA application, MPD for sunscreen containing iron oxide 3.2% was 5.78, compared with 0.33 for unprotected skin (p<.001) with a blue light protection factor of 21.

CONCLUSION:

The sunscreen containing iron oxide 3.2% afforded significant protection against blue light sensitivity induced by ALA application.

[Indexed for MEDLINE]

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