Topical formulation of retinyl retinoate employing nanostructured lipid carriers

Topical formulation of retinyl retinoate (RR) was developed with nanostructured lipid carriers (NLCs), composed of Compritol or Precirol as a solid lipid, canola oil as an oil, and Tween 80 as a surfactant. Hot high pressure homogenization method was efficiently employed to yield a homogenous nanodispersion in the size range of 230–300 nm with PDI values of <0.2, regardless of lipid selection. Precirol-based NLC (P-NLC) showed higher drug entrapment than that of Compritol-based NLC (C-NLC): RR encapsulation efficiency (%) of P- and C-NLC was 97.8 and 93.8 in average, respectively; drug loading (mg RR/g lipid) was 89.6 and 83.3 in average, respectively. Processing condition at relatively low temperature of 60 °C was a key factor for maintaining RR stability. Drug release of P-NLC was greater than that of C-NLC, even though both NLCs revealed controlled release pattern. Therefore, P-NLC system was considered as a suitable vehicle for topical drug delivery, especially for heat-labile ingredient like RR.