Preparation, characterization, and pharmacokinetics of oridonin‐loaded liposomes

The aim of this study was to prepare oridonin liposomes and evaluate the physicochemical characteristics and pharmacokinetics in rats. A three‐level, three‐factor Box–Behnken design was used to optimize the preparation of oridonin liposomes. A highly sensitive high‐performance liquid chromatographic quantification method using ultraviolet detection was established and validated for the determination of oridonin in rat plasma. Twelve Sprague–Dawley rats were randomly assigned and injected with 15 mg/kg of oridonin or oridonin liposomes via the tail vein. Pharmacokinetic parameters were estimated using a compartmental modeling approach using PKsolver software. The optimum conditions were as follows: soybean phospholipids/cholesterol ratio, 3.9:1; soybean phospholipids/drug ratio, 8.5:1; and soybean phospholipid concentration, 1.1%. Under these conditions, the mean particle size, polydispersity index, zeta potential, and encapsulation efficiency of oridonin liposomes were 170.5 nm, 0.246, −30.3 mV, and 76.15%, respectively. The pharmacokinetic results showed that liposomes could significantly prolong the elimination half‐life (from 2.88 ± 0.55 to 13.67 ± 3.52 h), increase the area under the concentration–time curve (from 1.65 ± 0.17 to 6.22 ± 0.83 μg h/ml), and decrease the clearance (from 6.62 ± 1.38 to 1.96 ± 0.24 L/kg h). The oridonin liposomes increased the elimination half‐life and area under the concentration–time curve and provided a reference for the development of drugs with a short half‐life.