A UHPLC-MS/MS method to determine FLZ major active metabolites in human plasma: application to a pharmacokinetic study

Pharmacokinetics and multi-peak phenomenon analysis of novel anti-Parkinson's drug FLZ after multi-dose in cynomolgus monkeys

The novel anti-Parkinson disease drug, FLZ, had a complicated drug absorption and metabolise process reported in single-dose studies. A multi-peak absorption peak phenomenon was found.This study focused on the multi-dose pharmacokinetics (PK) characteristics of FLZ, T1, and T2 in cynomolgus monkeys and raised discussion on its multi-peak absorption situation. Different doses of FLZ ranging from 75 to 300 mg/kg were administered orally to 16 cynomolgus monkeys. The whole treatment period lasted for 42 days with FLZ once a day.The primary metabolites of FLZ were Target1 (T1) and Target2 (T2), which had plasma exposure (calculated as AUC0-24, day 42) approximately 2 and 10 times higher than the parent drug. The proportion of plasma exposure increase was lower than the proportion of dose increase in FLZ, T1, and T2.Gender influenced its exposure (AUC0-24) with approximately 3-fold higher in males than females. There was no significant accumulation of T1 and T2. Enterohepatic Circulation (EHC) and gastrointestinal (GI) tract absorption may be involved in the mechanism of multi-peak characteristics.

Quantitative Determination of Quercitrin Levels in Rat Plasma Using UHPLC-MS/MS and its Application in a Pharmacokinetic Study after the Oral Administration of Polygoni Cuspidati Folium Capsules

BACKGROUND

Quercitrin is widely found in herbal medicines, and it is particularly important in the design of new therapeutic agents. Because of its wide range of biological activities, methods for detecting quercitrin and its pharmacokinetics in biological samples must be investigated.

OBJECTIVE

To develop and validate a sensitive and reliable ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for the quantitative determination of quercitrin levels in rat plasma and test its application in a pharmacokinetic investigation after the oral administration of Polygoni cuspidati folium capsules (HC).

METHODS

First, a rapid analytical method implementing UHPLC-MS/MS for the quantification of quercitrin levels in rat plasma was developed and validated. The analyte and internal standard (IS) tinidazole were extracted from rat plasma via protein precipitation with 800 μL of methanol and 50 μL of 1% formic acid solution. Chromatographic separation was performed using an Agilent ZORBAX C18 column within 4 min. Mass spectrometry was performed for quantification using a triple-quadrupole mass spectrometer employing electrospray ionization in the negative ion mode. The MRM transitions for quercitrin and IS were m/z 447.2→229.9 and m/z 246.0→125.8, respectively. The UHPLC-MS/MS method for the quantitative determination of quercitrin levels in rat plasma was then applied to investigate its pharmacokinetics after the oral administration of HC in rats.

RESULTS

The developed UHPLC-MS/MS method for detecting quercitrin in rat plasma was linear over the range of 0.1-160 ng/mL. The linear regression equation was Y = (0.7373 ± 0.0023)X - (0.0087 ± 0.0021) (r2 = 0.9978). The intra- and interday precision values were within 7.8%, and the recoveries of quercitrin and IS exceeding 67.3%. The UHPLC-MS/MS method was successfully applied to characterize the pharmacokinetic profile of quercitrin in eight rats after the oral administration of HC. The experimentally obtained values were fit to a one-compartment, first-order pharmacokinetic model, and they appeared to fit the concentration-time curve.

CONCLUSION

Quercitrin was proven to be stable during sample storage, preparation, and analytical procedures. The pharmacokinetic parameters suggested that quercitrin may be present in the peripheral tissues of rats.