Formulation optimization and the absorption mechanisms of nanoemulsion in improving baicalin oral exposure

Objective: The aim of this study was to optimize baicalin nanoemulsion, clarify the absorption mechanisms of nanoemulsion improving the exposure of baicalin, and assess the potential of employing nanoemulsion as nanosystem for insoluble drugs. Significance: A novel nanoemulsion formulation was successfully prepared to enhance oral exposure of baicalin. Methods: Pseudo-ternary phase diagrams were utilized to evaluate nanoemulsion area. Physicochemical properties of optimal nanoemulsion formulation were investigated. The exposure of baicalin from the nanoemulsion was compared with baicalin suspension. The in situ single-pass intestine perfusion (SPIP) method and chylomicron-blocked rat model were used to study the absorption mechanisms of nanoemulsion. Results: Baicalin nanoemulsion was nearly spherical in shape with the average droplet size of 58.43 nm, and the zeta potential was -8.18 +/- 1.2mV. The stability test showed that baicalin nanoemulsion was very stable. Pharmacokinetic study indicated that baicalin nanoemulsion showed 14.56-fold improvement in exposure in comparison to baicalin suspension. The results of SPIP and chylomicron flow blocking study showed that intestinal absorption and lymphatic transport process contributed to its systemic exposure. Conclusions: Based on the results, optimal nanoemulsion might be promising nanosystems for oral delivery of baicalin to satisfy clinical requirements.