An in vitro study on metabolic interaction between main active components of Salviae Miltiorrhizae Radix et Rhizoma and tacrolimus

The purpose of this study was to investigate the inhibitory effects of the main active components of Salviae Miltiorrhizae Radix et Rhizoma on the metabolism of tacrolimus mediated by CYP3 A4/5 enzyme, so as to predict the potential drug-drug interaction(DDI) in clinical use. First, the reversible inhibitory activities of five active components of Salviae Miltiorrhizae Radix et Rhizoma(tanshinone Ⅰ, tanshinone Ⅱ_A, cryptotanshinone, salvianolic acid B, dihydrotanshinone Ⅰ) on the metabolism of tacrolimus was investigated by using human liver microsomes(HLM) and recombinant human CYP3 A4/5 enzyme in vitro, then the dose-dependent inhibition of CYP3 A4/5 activity was calculated in HLM. Finally, the time-dependent inhibition(TDI) activities of five active components were studied in HLM through the robust single point inhibition test. In addition, a simple and rapid liquid chromatography tandem mass spectrometry method(HPLC-MS/MS) for the determination of tacrolimus was established in this study. The results showed that dihydrotanshinone Ⅰ had a strong inhibitory effect on the metabolism of tacrolimus in both HLM and rCYP3 A4/5 enzyme systems, and the inhibitory potential IC_(50) in HLM was 6.0 μmol·L~(-1), while the other four active components of Salviae Miltiorrhizae Radix et Rhizoma exhibited relatively weak inhibition on CYP3 A4/5 activity with inhibition rate less than 30% at 10 μmol·L~(-1). Furthermore, the TDI activity of five active components of Salviae Miltiorrhizae Radix et Rhizoma at 50 μmol·L~(-1) was 5.5%-15.9%. The above results suggested that clinical DDI between tacrolimus and Salviae Miltiorrhizae Radix et Rhizoma may occur when the active components of Salviae Miltiorrhizae Radix et Rhizoma achieved a relative high concentration in human. In conclusion, this study provided a data reference for the research on drug interaction of tacrolimus and Salviae Miltiorrhizae Radix et Rhizoma as well as rational drug use in clinical practice.