Determination of K15 Concentration in Rat Plasma by LC-MS/MS and Its Application in the Pharmacokinetics Study

OBJECTIVE To establish a LC-MS/MS method for the determination of (3AS, 4S, 6AR)-4H,4-methoxy furan3,4-B furan-2(3H)-ketone(K15) in rat plasma and for the pharmacokinetic study of K15. METHODS After different doses of K15 were administered by intragastric or intravenous injection, blood was taken from the orbital venous plexus of rats, and the concentration of K15 in rat plasma was determined by LC-MS/MS. DAS software was used to fit pharmacokinetics parameters such as AUC, C_max, T_max, T_1/2, and so on. RESULTS The endogenous impurities in plasma did not interfere with the determination of K15. The intra-day precision was ranged in 4.53%-6.60%, the inter-day precision was ranged in 5.19%-8.14%, and the accuracy was ranged in 96.10%-102.49%. The linear range of K15 was 25-1 000 ng·mL^-1, r=0.998 5. The lower limit of quantitation of K15 was 25 ng·mL^-1(RSD=12.7%, n=6). The bioavailability were 79.5%, 44.4% and 57.0% for administrated at the dose of 150, 450 and 1 000 mg·kg^-1, respectively. CONCLUSION The method is suitable for the analysis of K15 in rat plasma. The pharmacokinetics of K15 in rats is nonlinear dynamics. K15 has a certain amount of systemic exposure in rats after orally administrated to rats, but the systemic exposure dose not increase linearly with the amount of treated. When K15 is administered at 100 and 450 mg·kg^-1, there is no significant increase in C_max in vivo, but C_max increases significantly at 1 000 mg·kg^-1. With the increase of dosage, the T_1/2 of K15 increases significantly in rats, suggesting that the exposure time in rats increase significantly with the increase of dosage.