Simultaneous Determination of Eight Bioactive Components of Huangqin Decoction in Rat Plasma by Ultra‐high‐performance Liquid Chromatography‐tandem Mass Spectrometry and Its Application to Comparative Pharmacokinetic Study of Huangqin Decoction in Ul

Huangqin Decoction (HQD), a traditional Chinese medicine prescription, was first recorded in Treatise on Febrile Diseases 2000 years ago. It is widely used in the treatment of ulcerative colitis (UC). The purpose of the study was to investigate and compare the pharmacokinetic behaviors of the main bioactive components of HQD in UC and normal rats. A simple, rapid, and sensitive liquid chromatography-tandem mass spectrometry method was developed for the simultaneous determination of eight components of HQD in rat plasma. Analytes were separated on a C18 column under gradient elution with a mobile phase consisting of 0.1% formic acid in water and 0.1% formic acid in acetonitrile. Multiple reaction monitoring mode was used to acquire mass transitions. Method validation results showed good specificity and good linearity, with a limit of quantification ranging from 2.5 to 5.0 ng/mL which were sufficient for the pharmacokinetic study. The accuracy and precision were within 12.1% and 11.8%, respectively. Extraction recovery and matrix effect were from 81.8% to 98.8% and 83.6% to 98.4%, respectively. The relative error values of stability under different storage conditions were within 12.8%. The method was successfully applied to study the pharmacokinetics of eight components in UC and normal rat plasma after oral administration of HQD. Pharmacokinetic parameters of analytes were calculated. Results showed that the pharmacokinetic behaviors in UC and normal rats were significantly different, especially time to peak drug concentration (T_max), peak concentration (C_max), and area under the curve (AUC). In general, the C_max of all analytes and AUCs of most analytes in UC rats were markedly lower than in normal rats, which might be related to the pathological state of UC influencing the exposure levels of bioactive components of HQD, and reducing the absorption of them, resulting differences in pharmacokinetic behaviors. This study could provide a reference for the future clinical application of this classical traditional Chinese medicine formula.