Spray-Dried Powders Containing Tretinoin-Loaded Engineered Lipid-Core Nanocapsules: Development and Photostability Study

The influence of the spray-drying process on the ability of engineered lipid-core nanocapsules to protect tretinoin against UV degradation was evaluated. This approach represents a technological alternative to improve the microbiological stability, storage and transport properties of such formulations. Tretinoin-loaded lipid-core nanocapsules or tretinoin-loaded nanoemulsion were dispersed in lactose (10% w/v) and fed in the spray-drier to obtain a solid product (spray-dried powder containing tretinoin-loaded nanocapsules or nanoemulsion – SD-TTN-NCL or SD-TTN-NE, respectively). SD-TTN-NE showed a lower (p ≤ 0.05) percentage of encapsulation (89 ± 1%) compared to SD-TTN-NCL (94 ± 2%). Redispersed SD-TTN-NCL and SD-TTN-NE showed z-average sizes of 204 ± 2 nm and 251 ± 9 nm, which were close to those of the original suspensions (220 ± 3 nm and 239 ± 14 nm, respectively). Similar percentage of photodegradation were determined for tretinoin loaded in nanocapsules (26.15 ± 4.34%) or in the respective redispersed spray-dried powder (28.73 ± 6.19 min) after 60 min of UVA radiation exposure (p > 0.05). Our experimental design showed for the first time that spray-dried lipid-core nanocapsules are able to protect tretinoin against UVA radiation, suggesting that the drying process did not alter the supramolecular structure of the lipid-core nanocapsules. Such powders are potential intermediate products for the development of nanomedicines containing tretinoin.