Fig. 3

Administration of BZ formula with tamoxifen decreased endoxifen and 4-OH-tamoxifen concentrations in tumor-bearing mice. Nude mice were injected with ER⁺ human breast cancer MCF-7 cells and then treated with 4 mg/kg tamoxifen alone or in combination with BZ formula (2 or 8 g/kg) or paroxetine (4 mg/kg). The control group was treated with an equal volume of physiological saline. There were five animals per group. Blood was collected 1 h after oral administration on the last day of treatment and stored at -80 °C after centrifugation at 12000 rpm for 10 min. The serum tamoxifen and endoxifen concentrations were measured using HPLC-MS/MS. The tamoxifen, endoxifen, and 4-OH-tamoxifen concentrations after a 4 and b 8 weeks. *p < 0.05 compared to the tamoxifen group based on one-way ANOVA. Normalized concentrations of c tamoxifen, d 4-OH-taxoxifen, and e endoxifen in the tamoxifen group after treatment for 4 and 8 weeks