Formulation and Evaluation of Sunscreen Cream Based on Titanium Dioxide and Zinc Oxide Nanopowders Combined with Niacinamide

Excessive exposure to ultraviolet radiation can cause various forms of skin damage, highlighting the need for sunscreen preparations that provide effective photoprotection and possess suitable physical characteristics. The combination of titanium dioxide and zinc oxide nanopowders as inorganic ultraviolet filters with niacinamide as a supporting active ingredient has potential for development in sunscreen cream formulations. This study aimed to formulate and evaluate sunscreen creams containing a combination of titanium dioxide nanopowder, zinc oxide nanopowder, and niacinamide, as well as to determine the formulation with the best photoprotective activity. An experimental study was conducted by preparing three oil-in-water (O/W) cream formulations with varying concentrations of titanium dioxide and zinc oxide nanopowders: F1 (2%:4%), F2 (4%:2%), and F3 (3%:3%), while niacinamide was maintained at 4% in all formulations. The formulations were evaluated for organoleptic properties, homogeneity, pH, viscosity, spreadability, adhesion, emulsion type, stability using a heating–cooling test, Sun Protection Factor (SPF), Critical Wavelength (λc), and skin irritation. Quantitative data were analyzed using Two-Way Analysis of Variance (ANOVA). The results showed that all formulations exhibited acceptable physical characteristics and remained stable during four weeks of storage, with no phase separation observed after six heating–cooling cycles. The SPF values of F1, F2, and F3 were 39.4, 37.0, and 40.4, respectively, with all formulations providing ultra-level protection. F3 showed the highest SPF value and a Critical Wavelength of 385 nm, indicating broad-spectrum ultraviolet protection. The formulation variation significantly affected viscosity and spreadability (p<0.05), but did not significantly affect adhesion (p>0.05). The irritation test of F3 showed no signs of skin irritation in the subjects. Therefore, F3 was identified as the selected formulation, exhibiting favorable physical characteristics, good stability, ultra-level photoprotection, and potential broad-spectrum UV protection.