Qishen yiqi pills (QY pills) are a type of standardized cardiovascular herbal medicine, which contain four component herbs,
i.e., Astragalus membranaceus (Huangqi), Salvia miltiorrhiza (Danshen), Panax notoginseng (Sanqi), and Dalbergia odorifera (Jiangxiang).
After oral administration of QY pills, the in vivo exposure types of each component herb in rats were first uncovered and identified
according to a target-directed strategy based on hyphenated chromatography techniques. The dominated metabolites in urine, blood
and bile were originated from flavonoids of Huangqi and monomer phenolic acids of Danshen; no metabolites but parent drugs of Sanqi
ginsenosides, namely ginsenosides Rb1, Rd, Re and Rg1, notoginsenoside R1 and gypenoside XVII, were detected in rat urine and blood,
and the 20(S)-protopanaxatriol type ginsenosides (NR1, GRe, GRg1) could also be excreted to bile; the high liposolubility of volatile oils
from Jiangxiang restricted them to small intestine, liver and adipose tissues. The identification of metabolites in bio-samples was
achieved by exact mass measurement and detailed fragmentation pathway analyses. In specific conditions, not only the types of phase II
metabolism but also their conjugation positions could be determined by our established cleavage pathways, which lead to discriminate
the phase II metabolites of protocatechualdehyde for the first time. Based on the metabolite study in rats, the 4 main compounds (tanshinol,
astragaloside IV, GRb1 and GRg1) in QY pills were selected as pharmacokinetic markers. The PK results showed that their maximal
concentrations in blood were obtained within one hour, much shorter than the reported values in single herbs. The rat exposure was
proximately linear under the studied dosages from 1 to 6 g/kg.