The depigmentation effect of hydroquinone-loaded nanostructured lipid carriers (NLCs) on the rat skin

The goal of this research is the localization of hydroquinone (HQ) to the epidermis for the treatment of hyperpigmentation in rat skin. For this purpose, nanostructured lipid carrier (NLC) was selected for the dermal delivery of HQ. A 23 factorial design was used in this study, and eight NLCs were prepared with a cold homogenization technique. HQ entrapment efficiency (EE %), particle size, morphology, thermal behavior of NLCs, and permeability parameters through rat skin with NLC in comparison with HQ aqueous solution (HQ-S) with Franz diffusion cells were evaluated. Based on the optimization technique, the best NLC was selected and in the in vivo experiment, the depigmentation effect of optimized NLC in comparison with that of HQ-S was evaluated. The results showed that the main problem for HQ permeability was fast permeation and low concentration in the site of action. Partitioning from aqueous donor phase into skin rate was the limiting step for drug flux, and this can be solved using NLC. The decrease in maximum flux obtained by NLC was according to formulation 8. Regression analysis suggested a significant and direct effect of the S/L ratio and the percentage of liquid lipids on the drug loading. NLC decreased drug permeation through rat skin basically due to sustained release properties.