Development and validation of a novel UPLC-MS/MS method for quantification of delafloxacin in plasma and aqueous humour for pharmacokinetic analyses.

Acute bacterial skin and skin structure infections are one of the most frequent infectious disease requiring hospitalization for treatment. Delafloxacin is a clinically approved fluoroquinolone antibiotic for the treatment of ABSSSIs. In spite of being marketed since 2017, there is no published analytical method for quantification of delafloxacin in biological samples. Herein, a selective and sensitive UPLC-MS/MS method was developed and validated for quantitative analysis of delafloxacin in rat plasma and rabbit aqueous humour samples. The liquid liquid extraction (using ethyl acetate) was used for analyte extraction form rat plasma, whereas protein precipitation (acetonitrile) was used for aqueous humour samples preparations. An Acquity UPLC BEH C18 column was used for chromatographic separation of delafloxacin and internal standard (rivaroxaban). The mobile phase composition of acetonitrile (containing 0.1% formic acid) and 10 mM ammonium acetate in ratio of 60:40 were used for sample elution at 300 µL/min flow rate. The electrospray ionization operated in positive mode was used for sample ionization and detection of analyte and internal standard were performed by multiple reaction monitoring (MRM) mode. The MRM transitions were set to 441.14 > 379.09 and 436.89 > 144.87 for delafloxacin and internal standard, respectively. The method was validated as per USFDA guideline for bioanalytical method and all the evaluated parameters were within the acceptable ranges. The developed method in plasma was successfully used to analyze samples in pharmacokinetic study of newly developed stearic acid-chitosan solid lipid nanoparticles formulation of delafloxacin in rat.

Ultra-performance hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry for simultaneous determination of allopurinol, oxypurinol and lesinurad in rat plasma: Application to pharmacokinetic study in rats.

A fixed dose combination of lesinurad and allopurinol has been recently approved by USFDA and EMA for treatment of gout-associated hyperuricemia in patients who have not achieved target serum uric acid levels with allopurinol alone. In this study, an ultra-performance hydrophilic interaction liquid chromatography (UPHILIC) coupled with tandem mass spectrometry method was developed and validated for simultaneous determination of allopurinol, oxypurinol and lesinurad in rat plasma. Liquid liquid extraction using ethyl acetate as extracting agent was used for samples extraction procedure. Acquity UPLC HILIC column (100 mm x 2.1, 1.7µm) was used for separation of allopurinol, oxypurinol, lesinurad and internal standard (5-Florouracil). The mobile phase consisting of acetonitrile, water and formic acid (95:5:0.1, v/v/v), were eluted at 0.3 mL/min flow rate having total chromatographic run time of 3 min per sample. The analytes were detected on Acquity triple quadrupole mass spectrometer equipped with a Z-Spray electrospray ionization (ESI). The ESI source was operated in negative mode and multiple reaction monitoring was used for ion transition for all compounds. The precursor to product ion transition of m/z 134.94 > 64.07 for allopurinol, 150.89 > 41.91 for oxypurinol, 401.90 > 176.79 for lesinurad and 128.85 >41.92 for internal standard were used for identification and quantification. The calibration curves for all analytes were found to be linear with weighing factor of 1/x2 using regression analysis. The developed assay was successfully applied in an oral pharmacokinetic study of allopurinol, oxypurinol and lesinurad in rats.