Simultaneous determination of rivaroxaban and sitagliptin in rat plasma by LC–MS/MS and its application to pharmacokinetic drug-drug interaction study

A sensitive and accurate LC-MS/MS method was developed and validated for the simultaneous quantification of rivaroxaban (RIV) and sitagliptin (SIT) in rat plasma using apixaban as internal standard (IS). An Agilent Eclipse plus C18 column (2.1 × 100 mm, 3.5 µm, Agilent) was used for chromatographic separation with isocratic elution. Multiple reaction monitoring (MRM) using positive-ion ESI mode to monitor ion transitions of m/z 436.8→144.9 for RIV, m/z 407.7→173.8 for SIT, m/z 459.8→442.8 for IS. The procedure of method validation included selectivity, linearity, precision, accuracy, matrix effect, extraction recovery and stability were conducted according to the guidelines of EMA and FDA. The results indicated that no obvious drug-drug interactions occurred might be owing to their differences in metabolic pathways.

LIQUID CHROMATOGRAPHY TANDEM MASS SPECTROMETRY DETERMINATION METHOD OF BENCYCLOQUIDIUM BROMIDE: APPLICATION TO DRUG INTERACTION STUDY IN HUMAN

Objective: This study was conducted to develop a sensitive and effective LC-MS/MS method for the determination of bencycloquidium bromide (BCQB) and its application in pharmacokinetic drug interaction study between BCQB and paroxetine. Methods: The chromatographic separation was performed on Hedera ODS-2 C18 column with a mobile phase consisted of acetonitrile-10 mmol/l ammonium acetate containing 0.2% acetic acid (33:67, v/v) at 550 μl/min, and the plasma samples were processed using solid-phase extraction. The MS/MS transitions were m/z 330.2 → 142.0 for BCQB and m/z 344.2 → 156.1 for the I. S in positive ESI mode. Results: The validated method was linear over the concentration range of 2-1200 pg/ml with the correlation coefficient r2>0.998. The intra-and inter-batch precisions of the assay were lower than 8.2% and 9.1%, respectively. The lower limit of quantification (LLOQ) was 2 pg/ml. The stability data at different storage conditions of BCQB were within±5% RE. The mean AUC0-36 of BCQB was increased by approximately 33%, after the administration of BCQB alone and upon co-administration with paroxetine during the drug interaction study. Conclusion: The LC-MS/MS method validated in this study was robust, reproducible, accurate, precise and reliable and was successfully applied in the pharmacokinetic drug interaction studies.

The effect of potent CYP2D6 inhibition on the pharmacokinetics and safety of deutetrabenazine in healthy volunteers

Purpose Deutetrabenazine is a deuterated form of tetrabenazine with a confirmed lower rate of CYP2D6 metabolism of the active metabolites, α- and β-HTBZ. In this study, we assessed the effect of paroxetine, a potent CYP2D6 inhibitor, on the pharmacokinetics and safety of deutetrabenazine and its metabolites. Methods In this open-label sequential drug-drug-interaction study, 24 healthy adults who were CYP2D6 extensive or intermediate metabolizers received a single deutetrabenazine 22.5-mg oral dose on days 1 and 11 and a single paroxetine 20-mg oral daily dose on days 4–12. Pharmacokinetics of deutetrabenazine and its metabolites were assessed on days 1–4 and 11–14. Paroxetine trough concentrations were obtained pre-dose on days 9–13. Safety examinations occurred throughout the study. Results Paroxetine administered under steady-state conditions, increased exposure of the deuterated active metabolites, α-HTBZ (1.2-fold Cmax and 1.8-fold AUC0–∞) and β-HTBZ (2.1-fold Cmax and 5.6-fold AUC0–∞), and correspondingly, 1.6-fold Cmax and threefold AUC0–∞ for total (α + β)-HTBZ. Sixteen subjects reported 45 adverse events and most were mild. Headache was the most common AE reported 8 times by 7 subjects (5 following paroxetine alone; 2 following deutetrabenazine + paroxetine). Conclusions Paroxetine-induced increases in exposure to the active deutetrabenazine metabolites were less than those previously reported for tetrabenazine, a finding expected to reduce the burden of drug interaction. In addition, single doses of 22.5 mg deutetrabenazine, when given alone or in the presence of steady-state paroxetine (20 mg daily), were safe.