Enhanced liver-targeting via coadministration of 10-Hydroxycamptothecin polymeric micelles with vinegar baked Radix Bupleuri

Background: Vinegar baked Radix Bupleuri (VBRB) is a wildly used traditional Chinese medicine, it could be used as a meridian guided drug to enhance liver targeting efficiency of the delivered drug in addition to its therapeutic effect. Purpose: To investigate the liver targeting effect induced by VBRB via coadministration with 10-Hydroxycamptothecin loaded polymeric micelles. Methods: First of all, the inhibitory effect of VBRB on the activity of glutathione S-transferase (GST) was investigated in vitro to select the most effective extract. After oral administration of 10-Hydroxycamptothecin (HCPT) polymeric micelles with low, medium and high doses of VBRB, pharmacokinetic parameters, including the ratio of Cmax in the liver (Ce) and the relative uptake efficiency (RUE), were employed to assess the liver targeting efficiency. Results: It was found that VBRB extract BC1 has the strongest inhibition effect on GST activity in the five extracts. By coadministration of HCPT loaded micelles with three doses of BC1, the AUC(0-t), of HCPT in the liver raised by 42.5%, 23.0%, -0.2%, with RUE 1.45, 1.23, 1.02 for low, medium and high dose groups, respectively, indicating that low and medium dose of BC1 presented better liver-targeting enhancing effect than that of the high dose, which corresponded to the commonly used dose of VBRB in traditional Chinese medicine formulae. Conclusions: VBRB could effectively enhance the liver-targeting efficiency of HCPT loaded polymeric micelles after oral coadministration. Such a simple but effective strategy may enlighten on the potential use of meridian guided drug together with modern drug delivery system to achieve better active drug targeting.