Solid lipid nanoparticles for oral delivery of curcumin

Despite multiple medicinal benefits, the therapeutical utility of curcumin is strongly limited by its poor aqueous solubility and low oral bioavailability. Our work was focused on the development and characterization of solid lipid nanoparticles (SLN) for the encapsulation of curcumin for oral administration. Ultrasound technique was employed to prepare Compritol® 888 ATO SLN and formulation parameters as sonication time and drug concentration were evaluated and optimised. The physicochemical characterization of curcumin-loaded SLN in terms of particle size, drug loading capacity, drug entrapment efficiency, TEM analysis and in vitro drug release, was carried out. Stability was investigated on storage conditions (4 °C) over one month. Parallel artificial membrane permeability assay (PAMPA) was also carried out to predict gastrointestinal absorption. The optimized formulation showed average size below 300nm and good values of zeta potential (-33 mV) and encapsulation efficiency (80%). The presence of round shape SLN with homogeneous size distribution was confirmed by TEM analysis. There was no modification on the particle size neither on the zeta potential of the solid lipid nanoparticles, which maintained their original values over one month. Parallel artificial membrane permeability assay (PAMPA) showed a considerable increasing of the amount of curcumin permeated in the case of SLN suspension if compared with the saturated solution of curcumin used as control. We observe also a prolonged release profile that suggest that curcumin molecules are solubilized into the solid lipid matrix. Principal advantages of the developed SLN over the already reported nanocariers of curcumin are represented by the absence of usual solvents used for the preparation of the formulation and the use of very safe tensides such as Plunorics. For these reasons our SLNs offer a promising delivery system for enhancing the oral absorption of poorly soluble drugs curcumin.