Bisoctrizole (INN/USAN, INCI methylene bis-benzotriazolyl tetramethylbutylphenol, marketed as Tinosorb M, Parsol Max, Eversorb M, and Milestab 360, among others) is a phenolic benzotriazole that is added to sunscreens to absorb UV rays. It is a broad-spectrum ultraviolet radiation absorber, absorbing UVB as well as UVA rays. It also reflects and scatters UV.
Bisoctrizole is what is termed a hybrid UV absorber, which has been described as an organic UV filter produced in microfine organic particles (< 200 nm), like microfine zinc oxide and titanium dioxide. Where other organic UV absorbers dissolved in either the oily or aqueous phases, bisoctrizole dissolves poorly in both.
Hence, bisoctrizole is formulated in sunscreen preparations as a 50% suspension, the absorber added to the water phase, and mineral micropigments usually added to the oil phase. The bisoctrizole particles are stabilized by the surfactant decyl glucoside. The compound shows very little photodegradation, and has a stabilizing effect on other UV absorbers, octyl methoxycinnamate (octinoxate) in particular.
In primary research reports, bisoctrizole has been reported to minimally penetrate skin, and has been described as lacking estrogenic effects in vitro.
Bisoctrizole has not yet been approved by the U.S. Food and Drug Administration (FDA), but is approved in the EU and other parts of the world.Australian Regulatory Guidelines for OTC Medicines, Chapter 10.
References
External links Ciba® TINOSORB® M – Microfine UV absorber with Triple Action http://www.dermatologytimes.com/dermatologytimes/article/articleDetail.jsp?id=159652 NEW-WAVE SUNSCREENS – Active ingredient makers are frustrated by the long list of sunscreens and UV-A testing protocols that are still awaiting FDA decisions, C&EN Cover Story fda.gov