UHPLC-MS/MS Method for Quantifying Fangchinoline, Tetrandrine and Calycosin-7-O-β-D-Glucoside of Fangji Huangqi Decoction in Rat Plasma and Its Application to a Pharmacokinetic Study

Fangji Huangqi Decoction is composed of Stephaniae Tetrandrae Radix, Astragli Radix, Atractylodis Macrocephalae Rhizoma and Glycyrrhizae Radix Et Rhizoma. It is a classic traditional Chinese medicine formula for the treatment of chronic glomerulonephritis in China. However, its pharmacokinetic characteristics in vivo are still unclear. In this study, a method for quantifying fangchinoline, tetrandrine and calycosin-7-O-beta-D-glucoside, the main active constituents of Fangji Huangqi Decoction, in rat plasma by using ultrahigh-performance liquid chromatography-tandem mass spectrometry technique was developed. Plasma samples were processed with a deproteinization procedure using acetonitrile, followed by chromatographic separation on a Shim-pack XR-ODS C-18 column using gradient elution of 0.1% aqueous formic acid and acetonitrile at 0.4 mL/min. The analytes and internal standard, diphenhydramine hydrochloride, were detected using positive electrospray ionization in multiple reactions monitoring mode. The optimized mass transition ion-pairs (m/z) were 609.3/367.3 for fangchinoline, 623.3/174.3 for tetrandrine, 447.2/285.1 for calycosin-7-O-beta-D-glucoside and 256.2/167.1 for diphenhydramine hydrochloride, respectively. The developed method was validated for intraday and interday precision and accuracy whose values fell in the acceptable limits. Recovery efficiency of all the analytes was found to be >90.5%. Matrix effect was found to be negligible. Stability results showed that the analytes were stable under all conditions. The validated method was successfully used for studying the pharmacokinetics of the three compounds in rat plasma after oral administration of Fangji Huangqi Decoction.