Nanoemulsion and Nanoemulsion-Based Gel Formulations Containing Fluconazole and Daidzein Alone or in Combination: Preparation and in Vitro Characterization

Background and Aims: This study aimed to prepare and characterize (in vitro) nanoemulsion (NE) and NE-based gel (NEG) formulations containing fluconazole (FLU) and daidzein (DZ) alone or in combination for topical application on the skin or vaginal administration.Methods: The HPLC-UV method for simultaneously determining FLU and DZ was also developed and validated. We prepared the NE formulations using high-speed mixing and ultrasonication techniques. Then, gel formulations were prepared using sodium carboxymethyl cellulose (1%; NaCMC) as a gelling agent. In vitro characterization studies (the determination of zeta potential, droplet size, and PDI values for NE formulations, pH and viscosity measurements, FTIR analysis, and in vitro release studies) were performed on these formulations.Results: The prepared NE formulations’ droplet sizes were smaller than 120 nm, and the PDI values were smaller than 0.3. In addition, the zeta potential values for NE formulations were sufficient for physical stability. High EE% values (over 95% for both FLU and DZ) were obtained for NE and NEG formulations containing FLU and/or DZ. While the NE formulations showed Newtonian behavior, the NEG formulations showed pseudoplastic behavior.Conclusion: NE and NEG formulations were successfully prepared and in vitro characterized in our study.