Sunscreen formulations containing rice bran or soybean oil: rheological properties, spreadability and in vitro sun protection factor

The presence of rice bran or soybean oil at different concentrations (3 and 5 %) in gel-creams
containing benzophenone-3 (BZ-3) was evaluated. Gel-creams were prepared with Carbopol Ultrez®
(polymer) at 0.5 % (w/w). The influence of rice bran or soybean oil was evaluated on the pH values, rheological
behavior, spreadability and in vitro sun protection factor (SPF). All formulations showed a creamlike
aspect and pH between 6.5 and 7.0. Rheological analysis showed pseudoplastic Non-Newtonian behavior
for all formulations according to the Herschel-Bulkley model, regardless of the presence of the oil.
However, formulations containing BZ-3 showed higher shear rates and smaller spreadability factors than
blank formulations. On the other hand, formulations with higher concentration of vegetable oil showed
higher spreadability factors and smaller shear rates than formulations without it. The presence of oil
showed no influence on the SPF values of gel-creams.
Colegio de Farmacéuticos de la Provincia de Buenos Aires