CYP2C19 is involved in the effect of Wuzhi tablet (Schisandra sphenanthera extract) and its constituents on the pharmacokinetics of intravenous voriconazole.

The co-administration of voriconazole (VCZ) and Wuzhi tablet (WZ) is frequently prescribed for solid organ transplantation patients in China. However, the pharmacokinetic interactions between VCZ and WZ as well as its bioactive constituents, such as schisandrin A and schisandrol B, remain unknown. Therefore, the effects of WZ and the two lignans on the metabolism of VCZ and the potential role of cytochromeP450 (CYP450), especially cytochrome P450 2C19 (CYP2C19), were investigated. The results showed that WZ extensively inhibited the activities of CYP1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4. Noteworthy, 2.5 mg/mL WZ almost completely inhibited the activity of 2C19, and the inhibition ratio reached 78.6±3% and 63.5±4.6% for schisandrin A and schisandrol B at concentrations 100 μM, respectively. In addition, rats were treated with a single or consecutive 14 day oral dose of WZ (250 mg/kg), schisandrol B (10 mg/kg) and schisandrin A (10 mg/ kg). In rats treated with WZ, the AUC0-∞ value for intravenous VCZ dosing was increased by 80.2% (single dose, p < 0.05) and 66.4% (dosage for 14 day, p < 0.05) and the Cmax was increased by 10.5% (p < 0.05) and (20.6%, p < 0.05), respectively, much greater than that when VCZ (28 mg/kg) was given alone. Unexpectedly, the AUC and Cmax values after schisandrol B and schisandrin A treatment were significantly increased. However, the mRNA expression of liver CYP2C19 and the protein expression of liver CYP2C19 were surprisingly increased after treatment with WZ, schisandrol B and schisandrin A in rats. Therefore, attention should be paid to when WZ and VCZ are administered concomitantly, as dosage adjustment might become necessary. Further clinical study is warranted to validate the interaction between WZ and VCZ.