[Simultaneous determination of donafenib and its N-oxide metabolite in human plasma by liquid chromatography-tandem mass spectrometry].

Donafenib is the deuterium derivative of sorafenib, and is an anti-tumor drug in clinical trials. An accurate and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous determination of donafenib and its N-oxide metabolite in human plasma. The analytes and internal standards (sorafenib and sorafenib N-oxide) were extracted from plasma by protein precipitation with acetonitrile, and separated on a Gemini C18 (50 mm × 2.

[Determination of anaprazole in human plasma by LC-MS/MS in pharmacokinetic study].

Anaprazole is a proton pump inhibitor clinically used for curing peptic ulcer. A rapid, sensitive and convenient LC-MS/MS method was first established for the determination of anaprazole in human plasma. d(3), (13)C-anaprazole was used as internal standard (IS).

[A simple method for quantification of tapentadol in dog plasma by liquid chromatography-tandem mass spectrometry and evaluation of the effects of conjugated metabolites on tapentadol].

Tapentadol is a novel drug of opioid pain reliever, which is extensively metabolized primarily through conjugation. Tapentadol glucuronide and tapentadol sulfate are major drug-related metabolites in circulation. The objectives of this study were to develop a simple and rapid method to determine tapentadol and evaluate the effects of conjugated metabolites on tapentadol quantification using liquid chromatography with tandem mass spectrometry in dog plasma.

Effects of probenecid and cimetidine on the pharmacokinetics of nemonoxacin in healthy Chinese volunteers.

Purpose: To investigate the effects of probenecid and cimetidine on the pharmacokinetics of nemonoxacin in humans.

Methods: Two independent, open-label, randomized, crossover studies were conducted in 24 (12 per study) healthy Chinese volunteers. In Study 1, each volunteer received a single oral dose of 500 mg of nemonoxacin alone or with 1.

[Simultaneous determination of sivelestat and its metabolite XW-IMP-A in human plasma using HPLC-MS/MS].

A simple and rapid method was developed based on high performance liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) to determine sivelestat and its metabolite XW-IMP-A in human plasma. After a simple protein precipitation, the samples and internal standards were analyzed on a C18 column by a gradient elution program. The mobile phase consisted of 30% acetonitrile in methanol and 5 mmol · L(-1) ammonium acetate at a flow rate of 0.

[Determination of γ-aminobutyric acid in human plasma by LC-MS/MS and its preliminary application to a human pharmacokinetic study].

A rapid, sensitive and convenient LC-MS/MS method was developed for the determination of γ-aminobutyric acid (GABA) in human plasma. d2-γ-Aminobutyric acid (d2-GABA) was synthesized as internal standard (IS). After extraction from human plasma by protein precipitation with acetonitrile, all analytes were separated on a Luna HILIC column (100 mm x 3.

Effects of an Al(3+)- and Mg(2+)-containing antacid, ferrous sulfate, and calcium carbonate on the absorption of nemonoxacin (TG-873870) in healthy Chinese volunteers.

Aim: To evaluate the effects of an Al(3+)- and Mg(2+)-containing antacid, ferrous sulfate, and calcium carbonate on the absorption of nemonoxacin in healthy humans.

Methods: Two single-dose, open-label, randomized, crossover studies were conducted in 24 healthy male Chinese volunteers (12 per study). In Study 1, the subjects orally received nemonoxacin (500 mg) alone, or an antacid (containing 318 mg of Al(3+) and 496 mg of Mg(2+)) plus nemonoxacin administered 2 h before, concomitantly or 4 h after the antacid.

Liquid chromatography-tandem mass spectrometry simultaneous determination of repaglinide and metformin in human plasma and its application to bioequivalence study.

A simple, sensitive, selective, and reproducible liquid chromatography-tandem mass spectrometric method was developed for the simultaneous determination of repaglinide and metformin in human plasma using d5-repaglinide and d6-metformin as internal standards (ISs). After a simple protein precipitation using acetonitrile as the precipitation solvent, both analytes and ISs were separated on a Venusil ASB C 18 (150 mm x 4.6 mm, 5 microm) via gradient elution using acetonitrile--10 mmol x L(-1) ammonium acetate as the mobile phase.

Pharmacokinetics of tacrolimus converted from twice-daily formulation to once-daily formulation in Chinese stable liver transplant recipients.

Aim: To evaluate the pharmacokinetics of tacrolimus in Chinese stable liver transplant recipients converted from immediate release (IR) tacrolimus-based immunosuppression to modified release (MR) tacrolimus-based immunosuppression.

Methods: Open-label, multi-center study with a one-way conversion design was conducted. Eighty-three stable liver recipients (6-24 months post-transplant) with normal renal and stable hepatic function were converted from IR tacrolimus twice-daily treatment to MR tacrolimus once-daily treatment on a 1:1 (mg: mg) total daily dose basis.

Influence of omeprazole on pharmacokinetics of domperidone given as free base and maleate salt in healthy Chinese patients.

Aim: To investigate the influence of omeprazole on the pharmacokinetics of domperidone given as free base and maleate salt.

Methods: An open, randomized, 2-period crossover study with a washout period of 7 d was conducted in 10 healthy Chinese, male patients. In each study period, the patients were administered a single oral dose of 10 mg domperidone as free base or maleate salt on d 1, 20 mg omeprazole twice daily on d 2 and 3, and once on d 4.