This study investigates the impact of emulsifier substitution and booster concentration on sunscreen characteristics, including physical properties, the sun protection factor (SPF), and sensory attributes. The impact of substituting Polysorbate^® 80 with Beautyderm^® K10 as an emulsifier in sunscreen formulations, along with the effect of increasing concentrations of the Sunhancer™ Eco SPF Booster, was thoroughly evaluated. Spectrophotometric methods were used to determine SPF, while texture analysis and rheological measurements assessed physical characteristics. Stability was evaluated using a centrifuge stress test, and sensory analysis was conducted on the top-performing formulation. The results indicated that the choice of emulsifier and booster concentration significantly influenced SPF values and stability. The influence of booster concentration on textural properties was most significant in formulations containing Beautyderm^®. Centrifuge testing revealed phase separation in certain formulations. Notably, the formulations that exhibited the greatest stability were those in which Beautyderm^® was combined with either Polysorbate^® or Span^®. Following the stability test results, the cream formulation containing Beautyderm^® and Polysorbate^® as emulsifiers was further evaluated through sensory analysis. Independent assessors determined that the sensory attributes of the cream did not undergo significant changes even when zinc oxide was added at a concentration of 1% (w/w) to the formulation. These findings underscore the importance of carefully selecting emulsifiers and boosters to achieve high sun protection efficacy, stability, and desirable sensory properties in sunscreen formulations.

The stability of sunscreen formulations is a key factor influencing their protective efficacy and safety, particularly under UV exposure, which can induce photodegradation of UV filters. (1) Background: This study aimed to evaluate the effect of selected antioxidants (stabilized vitamin C, carrot macerate, and ferulic acid) on the sun protection factor (SPF) and photostability of sunscreen formulations. (2) Methods: Four oil-in-water creams with identical compositions, except for the antioxidant type, were prepared and characterized in terms of SPF, rheological behavior, pH, conductivity, stability, and sensory properties. SPF was determined using an in vitro spectrophotometric method before and after UV irradiation (30 and 120 min). (3) Results: Antioxidant incorporation increased initial SPF, with ferulic acid providing the most significant enhancement. After UV exposure, all formulations exhibited a decrease in SPF. However, the formulation containing ferulic acid maintained the highest absolute SPF value, indicating superior photostability. In contrast, vitamin C showed the greatest reduction in SPF, suggesting lower stability under irradiation. Physical characterization confirmed appropriate properties of the formulations, and sensory analysis identified the ferulic acid formulation as the most acceptable. (4) Conclusions: Ferulic acid demonstrated the most favorable impact on sunscreen performance, suggesting its potential as an effective multifunctional ingredient in sunscreens.

This study focuses on the development and characterization of microemulsion gel systems incorporating the model drug lidocaine. Microemulsions were prepared via the standard phase titration method using various oil phases, surfactants, and co-surfactants, with demineralized water as the aqueous component. The primary objective was to assess the physical properties of the resulting gels and compare their drug release profiles to conventional gel formulations. The study examined the impact of varying surfactant and co-surfactant types, as well as the presence of the active pharmaceutical ingredient, on gel characteristics. Physical properties were evaluated through texture analysis and rheological measurements, while drug release was determined using Franz diffusion cells. Results showed that while the physical properties of microemulsion gels remained largely consistent across formulations, significant differences were observed in lidocaine liberation, highlighting the potential of microemulsion gels to modulate drug release behavior.