Nimodipine loaded lipid nanospheres prepared by solvent diffusion method in a drug saturated aqueous system

To overcome the disadvantages such as lower drug entrapment efficiency (EE) of lipid nanospheres prepared by conventional solvent diffusion method, a solvent diffusion method in drug saturated aqueous system was developed. Nimodipine was used as a model drug to incorporate into lipid nanospheres. The monostearin (MS) solid lipid nanoparticles (SLN) produced by conventional method under different production temperature only showed 24.40–30.21 wt% EE, and relatively higher EE was achieved when the production temperature was 0 °C. The EE could be enhanced by the incorporation of liquid lipid (caprylic/capric triglycerides, CT) into SLN and the employing of drug saturated dispersion medium. The nanostructured lipid carrier (NLC) with higher CT content indicated the highest EE as the drug saturated aqueous solution was used as dispersion medium. The differential scanning calorimetry (DSC) results demonstrated the present method could improve the drug encapsulation into lipid nanospheres. In vitro drug release experiments indicated the present preparation method could delay the drug release rate from lipid nanospheres, and the drug release rate could adjust by the CT content in lipid nanospheres. The highest drug loading (DL) was reached up to 4.22 wt% when 8 wt% drug was charged in the preparation of lipid nanospheres.