Development and evaluation of self-nanoemulsifying drug delivery system of rhubarb anthraquinones

Rhubarb anthraquinones (RhA) as a group were formulated in nanoemulsion based system with the aim of improving its solubility and oral bioavailability. RhA loaded nanoemulsion (RhA-NE) was prepared using spontaneous nanoemulsification method. Solubility of RhA in oils, surfactants and co-surfactants was determined to select nanoemulsion components. Surfactants and co-surfactants were screened for their ability to emulsify selected oily phase. Pseudo-ternary phase diagrams were constructed to identify area of nanoemulsification. A four-factor-five-level central composite design was carried out to attain optimal formulation. The optimized formulations of RhA-NE consisted of capryol 90/ethyl oleate containing RhA as oil phase, cremophor RH 40 as surfactant, transcutol HP as co-surfactant, oleic acid as stabilizer and distilled water as water phase. The RhA-NE was characterized by dynamic light scanning, transmission electron microscope, solubilizing capacity, encapsulation efficiency, drug loading and stability. The optimized RhA-NE can obviously enhance solubilization of RhA in distilled water. The appearance and RhA contents were basically unchanged after 60-day storage at room temperature in brown bottle. More than 50% RhA released from nanoemulsion within 240 h in vitro. Pharmacokinetics in rats showed that the Cmax and AUC of RhA-NE were enhanced compared to that of RhA suspension.

The optimized rhubarb anthraquinones loaded nanoemulsion can obviously enhance solubilization of rhubarb anthraquinones in distilled water. Pharmacokinetics in rats showed that the Cmax and AUC of rhubarb anthraquinones loaded nanoemulsion were enhanced comparing to rhubarb anthraquinones suspension.265