A novel strategy for encapsulating poorly soluble drug into nanostructured lipid carriers for intravenous administration.

The present study aimed to formulate dexamethasone (DXM), a poorly soluble drug, into nanostructured lipid carriers (NLCs) for intravenous administration by employing a phospholipids complex. Initially, dexamethasone-phospholipids complex (DPC) was synthesized and characterized. Subsequently, DPC was entrapped into NLCs and the process was optimized using spherical symmetric design-surface response methodology. Then, the characteristics, in vitro release behavior and physical stability of the optimized DPC loaded NLCs (DPC-NLCs) were investigated. Comparison between DPC-NLCs and free DXM loaded NLCs was also conducted in the aspects of particle size, entrapment efficiency (EE), drug loading efficiency (DL), initial release and zeta potential. The results showed the optimized DPC-NLCs were prepared with an average size of 189.33 +/- 0.58 nm, EE of 89.82 +/- 1.64%, DL of 2.13 +/- 0.13% and good physical stability for 30 days. In vitro release profile exhibited an initial burst release followed by a prolonged release. Compared with free DXM loaded NLCs, the EE and DL of DPC-NLCs were higher while the initial release was lower. These advantages of DPC-NLCs proved the phospholipids complex played an essential role in NLCs formulation and showed the potential for intravenous administration of poorly soluble drugs.