Biodegradable polymer nanocapsules containing a sunscreen agent: preparation and photoprotection

Biodegradable polymer nanocapsules containing the lipophilic sunscreen, Parsol MCX (OMC), as the oil core were prepared by solvent displacement. We investigated the influence of polysorbate 85 (P-85) and poloxamer 188 (P-188) as stabilizing agents, the OMC loading capacity and the photoprotective potential of the formulations. The formation of nanocapsules is probably due to an interfacial instability arising from rapid diffusion of the solvent across the interface. The effectiveness of the stabilizing agents was attributed to their ability to inhibit coalescence during solvent diffusion. P-85 was a better stabilizer of poly(epsilon-Caprolactone)-nanocapsules than P-188. The OMC loading capacity was high (99+/-1% of OMC initial concentration). The in vitro release of OMC-nanocapsules is governed by hydrophobicity and crystallinity of the polymer and by the high lipophilicity of the drug. The OMC-nanocapsules provided partial protection against UV-induced erythema, in a manner significantly better than a conventional gel.