A new approach for drying of nanostructured lipid carriers (NLC) by spray-drying and using sodium chloride as the excipient

Abstract

Nanostructured lipid carriers (NLCs) are effective encapsulation systems for many lipophilic bioactive compounds. In this study, a new approach of creating spray-dried NLCs was developed by mixing them with salt prior to dehydration. A NLC/NaCl suspension was passed through a spray drier at an inlet temperature of either 110 or 180 °C, and at a feed flow rate of either 5 or 15 mL/min. Scanning electron microscopy (SEM) analysis of the resulting powders indicated that they contained particles with different dimensions, morphologies, and aggregation states. For instance, hollow composite spheroids were obtained at a feed rate of 5 mL/min (110 and 180 °C), while agglomerated crystals (110 °C) or discrete fine crystals (180 °C) were obtained at a feed rate of 15 mL/min. The presence of the NLCs within the powder particles was assessed by ash analysis, FTIR spectroscopy, and backscattered SEM analysis. Compared to the original samples, the particle sizes of the NLCs increased after redispersion of the spray-dried powders in water, but the mean diameters were still relatively low (<220 nm). Analysis of powder properties (Carr's compressibility index, Hausner ratio, and angle of repose) showed that the spray-dried NLC samples had good flowability. This study shows that powdered NLC systems can be successfully produced by spray-drying the lipid nanoparticles using NaCl as an excipient.