Abstract
In this study, we investigated the effect of silybin on the pharmacokinetics of brexpiprazole and the underlying mechanism in rats. Two groups of animals received silybin at different doses (50 mg/kg, 25 mg/kg) for 2 weeks, while another group was given vehicle alone. After that, rats were intragastrically administrated with 2 mg/kg brexpiprazole. Then, the tail blood and liver tissues were collected from each rat at different time points. Brexpiprazole in serum was determined by an established UPLC-MS/MS assay. Finally, pharmacokinetic parameters of animals in each group were figured out. The results show that silybin remarkably changed the pharmacokinetic properties of brexpiprazole, especially at the highest dose. AUC and Cmax in the combination group with 50 mg/kg silybin were enhanced approximately 4 times as much as after a single dose of brexpiprazole, p < 0.05. Meanwhile, total liver protein of each sample was extracted, and was subjected to immunoblotting assay for probing CYP3A4 and CYP2D6. Therein CYP3A4 was significantly downregulated compared to the control group. Overall, silybin can increase blood concentration of brexpiprazole in rat by downregulating its main metabolic enzyme CYP3A4. Therefore, the maintenance dose of brexpiprazole should be decreased while co-treating with silybin.