Preparation, optimization and in vivo anti-inflammatory evaluation of hydroquinone loaded microemulsion formulations for melasma treatment

The aim of the study is to evaluate the strengthening of penetration of the epidermis through the formulas containing hydroquinone in melasma treatment and development of alternative new carrier systems. During preparation of hydroquinone loaded microemulsions, isopropyl myristate (IPM) as oil phase, Cremophor EL, Span 20, Span 80 and Tween 20 as surfactant, ethanol as co-surfactant, distilled water as aqueous phase were used. Furthermore, in vitro drug release studies were performed. As results of the study, it was measured that conductivity between 16 ± 2.51 and 42.1 ± 2.67, viscosity between 8.97 ± 0.082 and 51.76 ± 0.04, pH between 3.3 ± 0.436 and 5.7 ± 0.2 and refractive index between 1.4032 ± 0.0002 and 1.4299 ± 0.0002. Formulations showed that zeta potential between-0.461 ± 0.009 and 0.359 ± 0.223, PDI between 0.08 ± 0.02 and 0.196 ± 0.067, and droplet size between 24.27 ± 3.559 and 324.9 ± 16.8 nm. Moreover, in vitro drug release studies showed that formulation M2 released 87.405 % of the drug at the end of the 24h. According to results of histopathological analysis, formulations were found convenient for the usage. According to results of our study, hydroquinone loaded microemulsions can be seen as a promising alternative for the treatment of melasma disease.