Preparation of hydroxypinacolone retinoate nanoemulsion with high stability, low irritation and high permeability

Nanoemulsions (NE) are attractive for cosmetic applications due to ensure improved steadiness and efficient penetration of bioactive components, leading to enhanced efficacy. Hydroxypinacolone Retinoate (HPR) is an ingredient with great potential in combating the effects of aging, but its formulation is often unstable. In order to improve the solubility, bioavailability and stability of HPR, two kinds of oil-in-water (O/W) nanoemulsions were developed by high-pressure homogenization technology. These two nanoemulsions used GTCC and dimethyl isosorbide as the oil phase, respectively, which leads to different properties. Average particle size was (101 ± 0.02 nm) (72 ± 0.03 nm), Zeta potential was (-16.23 ± 0.15) (-18.21 ± 0.02). Particle size, polydispersity index, and potential were recorded for seven different conditions, which showed good physical and chemical stability over 90 days. Compared to free HPR, the retention of NE at 60 days under light and 45 °C was improved by 10% (G-NE) and 8% (D-NE), respectively. Encapsulation resulted in improved stability and bioavailability of HPR. In the in vitro diffusion cell assay, the skin retention of the two nanoemulsions was 17.02 μg/mL and 29.17 μg/mL, which was much higher than that of the free HPR, which was 4.08 μg/mL (P<0.01). Both the erythrocyte hemolysis test and the human patch test showed that the nanoemulsion reduced the stimulation of HPR. This study provides a practical method to increase the utilization of HPR in cosmetic formulations, thereby improving efficacy.