Abstract

Nanostructured lipid carriers (NLC) are a recent approach for the delivery of poorly soluble drugs with low oral bioavailability. The oral antidiabetic Repaglinide (RPG) was loaded into NLC using emulsification-ultrasonification technique. A design of experiment was constructed to study the formulation variables. The influence of the liquid lipid to the solid lipid ratio and the concentration of the surfactant on mean particle size, zeta potential and drug entrapment efficiency was demonstrated. The mean particle size ranged from 182 ± 7.9 nm to 452 ± 66.1 nm. All particles were negatively charged and the zeta potential values ranged from – 7.9 ± 0.9 mV to – 44.4 ± 6.2 mV. The highest entrapment efficiency was obtained with the minimum solid lipid to liquid lipid ratio and lowest surfactant concentration. All RPG–NLC formulae showed biphasic time dependent in vitro release and the studied factors were optimized and the optimum formula was evaluated for in vitro release and crystallinity. The in vitro release of the optimized formula fitted to the Higuchi diffusion model. In conclusion, this study showed the potential of NLC as a carrier for controlled release of RPG.

Key words: Nanostructured lipid carriers, Emulsification – Ultrasonification, Repaglinide, Optimization, DSC