Bisoctrizole

Bisoctrizole (USAN, Tinosorb® M, INCI Methylene Bis-Benzotriazolyl Tetramethylbutylphenol) is a chemical which is added to sunscreens to absorb UV rays. It's marketed by Ciba Specialty Chemicals.

Bisoctrizole is a broad spectrum ultraviolet radiation absorber, absorbing UVB as well as UVA rays. It also reflects and scatters UV. Bisoctrizole is a hybrid UV absorber. It's produced as small particles (< 200 nm), like microfine zinc oxide and titanium dioxide. And it is organic like most sunscreen actives. It is added to the water phase of a sunscreen as a 50% suspension, while mineral micropigments are usually added to the oil phase.

Bisoctrizole shows very little photodegradation and has a stabilizing effect on other UV absorbers, octyl methoxycinnamate (octinoxate) in particular.

Unlike some other organic sunscreen actives, it shows no estrogenic effects in vitro.

Bisoctrizole is not approved by the FDA, but is approved in the EU and other parts of the world.