Nanostructured lipid carriers enhances the safety profile of tretinoin: in vitro and healthy human volunteers' studies.

Aim: To enhance the tretinoin (TRE) safety profile through the encapsulation in nanostructured lipid carriers (NLC). Materials & methods: NLC-TRE was developed using a 23 experimental factorial design, characterized (HPLC, dynamic light scattering, differential scanning calorimetry, x-ray diffraction analysis, transmission electron microscopy, cryo-transmission electron microscopy) and evaluated by in vitro studies and in healthy volunteers. Results: The NLC-TRE presented spherical structures, average particle size of 130 nm, zeta potential of 24 mV and encapsulation efficiency of 98%. The NLC-TRE protected TRE against oxidation (p < 0.0001) and promoted epidermal targeting (p < 0.0001) compared with the marketed product, both 0.05% TRE. The in vitro assay on reconstructed human epidermis and the measurement of transepidermal water loss in healthy volunteers demonstrated an enhanced safety profile in comparison to the marketed product (p < 0.0002). Conclusion: The NLC-TRE enhances the epidermal targeting and safety profile of TRE, representing a potential safer alternative for the topical treatment of skin disorders using TRE.