Targeted pharmacokinetics of polymeric micelles modified with glycyrrhetinic acid and hydrazone bond in H22 tumor-bearing mice

Liver cancer is one of the most common malignant tumors. Chemotherapy drugs have been widely used in the anti-hepatoma research. However, low targeting efficiency and serious adverse reaction are their main drawbacks. Liver tumor was proved to have a slightly acidic microenvironment (pH 4.5-5.5) and many glycyrrhetinic-acid-specific binding sites. Therefore, in the present study, the glycyrrhetinic acid- and hydrazone bond-modified micelles were designed. mPEG-HZ-PLA and GA-PEG-PLA copolymer were synthesized to prepare glycyrrhetinic-acid-modified pH-sensitive polymeric micelles (GA-PEG-HZ-PLA). The targeted pharmacokinetics was used to evaluate the effect in hepatoma 22 tumor-bearing mice after the micelles were administered intravenously. The contents of coumarin-6 in blood and tissues were determined through high-performance liquid chromatography using a fluorescence detection (HPLC-FLD) with coumarin-30 as inner standard. The micelles have shown long-circulation effects and two-department models. In the targeting pharmacokinetics, the relative intake efficiency, targeted efficiency, relative targeting efficiency, and concentration ratio of GA-PEG-HZ-PLA in the tumor were 3.24, 4.04, 3.00, and 2.47, respectively. We have demonstrated that GA-PEG-HZ-PLA was more effectively accumulated in the liver and tumor. Thus, the prepared active-targeted and pH-sensitive micelles modified with glycyrrhetinic acid structure and hydrazone bond are promising tools for effective liver cancer therapy.