1. We aimed to investigate the regulatory effects of Guanxinning injection (GXNI) on activities of cytochrome P1A2 (CYP1A2), CYP2C11, CYP2D1 and CYP3A1/2 by probe drugs in rats in vivo and in vitro. 2. GXNI-treated and blank control groups were administered GXNI and physiological saline by caudal vein for 14 days consecutively, then they were given the probe drugs of caffeine (10 mg/kg), tolbutamide (10 mg/kg), metoprolol (20 mg/kg) and dapsone (10 mg/kg) by intraperitoneal injection. The blood samples were collected at different times for ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis. Changes of the pharmacokinetics parameters between the GXNI-treated and the blank control groups were used to evaluate the effects of GXNI on the four CYP450 isoforms in rats in vivo. After blood collection, the livers of rats were taken and made microsomes for in vitro tests. The relevant metabolites of phenacetin, tolbutamide, dextromethorphan and testosterone were analyzed quantitatively by high-performance liquid chromatography (HPLC) after microsome incubation. The statistical differences between the two groups were observed to detect the effects of GXNI on the four CYP450 isoforms in rats in vitro. 3. The in vivo and in vitro results demonstrated that GXNI could induce CYP1A2 activity in rats, but had no significant effects on CYP2C11, CYP2D1 and CYP3A1/2.
