This formulation uses a mix of emulsifiers that are both nonionic—i.e., ceteareth 20/cetearyl alcohol blend, and cationic—i.e., distearyldimonium chloride. Cationic emulsifiers benefit the formulation since they are more substantive to skin, imparting a richer feel and requiring lower levels of preservatives. However, cationic emulsifiers can be more irritating than their nonionic and anionic counterparts, so care must be taken when formulating these emulsions.
Hydroxypropyl starch phosphate is used to help stabilize the emulsion and increase viscosity; a combination of water phase thickeners may further optimize stability, specifically at elevated temperatures. Octocrylene has triplet quenching properties that stabilize avobenzone when exposed to UV.
Additional ingredients in combination with octocrylene could better stabilize the avobenzone; one such ingredient is polyester-8, a copolymer of adipic acid and neopentyl glycol, which also has triplet quenching properties.