In vitro penetration and bioavailability of novel transdermal quercetin-loaded ethosomal gel

Quercetin has been widely used to treat many diseases because of its high antioxidant activity. However, it has low oral bioavailability and penetration through the skin. The aim of this research was to enhance penetration and bioavailability of quercetin using transdermal ethosomal gel. Three ethosomal formulae, E1 (1 %), E2 (1.5 %) and E3 (2 %) with different concentration of quercetin were prepared using thin-film hydration method. Their physical properties were characterized, and then a selected ethosomal formula was incorporated into a gel dosage form. Two gels, one ethosomal and the other non-ethosomal were prepared. In vitro penetration using Franz diffusion cells and bioavailability study in Sprague Dawley male rats were carried out. Results showed that E2 was the chosen formula to be incorporated into the gel dosage form. According to the in vitro penetration study, the diffusion flux of quercetin from the ethosomal and non-ethosomal gels were 343.35±17.69 ng/cm²/h and 120.68±11.92 ng/cm²/h, respectively (P<0.05). In the bioavailability study, ethosomal gel showed higher maximum concentration (C_max) and area under curve (AUC_0-t) when compared to non-ethosomal gel and oral suspension. C_max from the ethosomal gel, non-ethosomal gel, and oral suspension were 413.49±28.64, 189.46±49.68, and 61.92±14.31 ng/ml, respectively (P<0.05). AUC_0-t from the ethosomal gel, non-ethosomal gel, and oral suspension were 4035.15±560.60, 584.87±265.46, and 431.21±239.85, respectively (P<0.05). In conclusion, ethosomal gel could increase penetration and bioavailability of quercetin compared to non-ethosomal gel.