Polyamide nanocapsules and nano-emulsions containing Parsol MCX and Parsol 1789: in vitro release, ex vivo skin penetration and photo-stability studies

Purpose: To prepare polyamide nanocapsules for skin photo-protection, encapsulating α-tocopherol, Parsol® MCX (ethylhexyl methoxycinnamate) and/or Parsol® 1789 (butyl methoxydibenzoylmethane). Methods: Nanocapsules were obtained by combining spontaneous emulsification and interfacial polycondensation reaction between sebacoyl chloride and diethylenetriamine. Nanoemulsions used as control were obtained by the same process without monomers. The influence of carrier on release rate was studied in vitro with a membrane-free model. Epidermal penetration of encapsulated sunscreens was ex vivo evaluated using Franz diffusion cells. Ability of encapsulated sunscreens to improve photo-stability was verified by comparing percentage of degradation after UV radiation exposure. Results: Sunscreen-containing nanocapsules (260-400 nm) were successfully prepared; yield of encapsulation was >98%. Parsol® MCX and Parsol® 1789 encapsulation led to decreased release rate by up to 60%in comparison with nano-emulsion and allowed minimum penetration through pig ear epidermis. Presence of polyamide shell protected encapsulated sunscreen filters from photo-degradation without affecting their activity. Conclusions: Encapsulation of Parsol® MCX and Parsol® 1789 into oil-core of polyamide nanocapsules allowed protection from photo-degradation, controlled release from nanocapsules, and limited penetration through pig ear epidermis. © Springer Science+Business Media, LLC 2011.