title: An improved LC-MS/MS method for the simultaneous determination of pyrazinamide, pyrazinoic acid and 5-hydroxy pyrazinoic acid in human plasma for a pharmacokinetic study.
abstract: In the present work the plasma levels of PZA and its two active metabolites, pyrazinoic acid (PA) and 5-hydroxy pyrazinoic acid (5-OH PA) were determined by a sensitive and rapid LC-MS/MS method. The analytes and their labeled internal standards were extracted from 200μL plasma samples by liquid-liquid extraction with methyl tert-butyl ether: diethyl ether (90:10, v/v) under acidic conditions. Their separation was achieved on a Zorbax Eclipse XDB C18 (100×4.6mm, 3.5μm) column using methanol and 0.1% acetic acid (65:35, v/v) as the mobile phase within 4.0min. Detection and quantitation were done by multiple reaction monitoring on a triple quadrupole mass spectrometer following the transitions, m/z 124.1→81.1,m/z 125.0→80.9 and m/z 141.0→81.0 for PZA, PA and 5-OH PA respectively in the positive ionization mode. All the analytes were baseline resolved with a resolution factor of 3.3 and 6.4 between PZA and its metabolites, PA and 5-OH PA respectively. The calibration curves were linear from 0.100-30.0μg/mL, 0.03-9.00μg/mL and 0.002-0.600μg/mL for PZA, PA and 5-OH PA respectively with r(2)≥0.9980 for all the analytes. The intra-batch and inter-batch accuracy and precision (% CV) across quality controls varied from 93.5-106.7% and 1.10-4.57 respectively for all the analytes. The mean extraction recovery of PZA, PA and 5-OH PA was 83.7%, 89.2% and 80.8% respectively, which was consistent at higher as well as lower concentration levels. The% change in the stability of analytes under different storage conditions ranged -6.7 to 7.1 for all the analytes. The method was applied to assess the comparative bioavailability of a 500mg PZA test and reference formulation in healthy subjects. The assay reproducibility was also tested by reanalysis of 22 incurred subject samples.
authors.affiliation: Department of Chemistry, School of Sciences, Gujarat University, Ahmedabad 380009, India.
authors.forename: Priyanka A
authors.initials: PA
authors.lastname: Shah
authors.affiliation: Department of Chemistry, School of Sciences, Gujarat University, Ahmedabad 380009, India.
authors.forename: Primal
authors.initials: P
authors.lastname: Sharma
authors.affiliation: Department of Chemistry, School of Sciences, Gujarat University, Ahmedabad 380009, India.
authors.forename: Jaivik V
authors.initials: JV
authors.lastname: Shah
authors.affiliation: Department of Chemistry, St. Xavier's College, Navrangpura, Ahmedabad 380009, India.
authors.forename: Mallika
authors.initials: M
authors.lastname: Sanyal
authors.affiliation: Department of Chemistry, School of Sciences, Gujarat University, Ahmedabad 380009, India. Electronic address: pranav_shrivastav@yahoo.com.
authors.forename: Pranav S
authors.initials: PS
authors.lastname: Shrivastav
mesh_terms: D002138:Calibration; D002853:Chromatography, Liquid / Q000379:methods*; D006801:Humans; D011718:Pyrazinamide / Q000031:analogs & derivatives* / Q000097:blood* / Q000493:pharmacokinetics; D011786:Quality Control; D012015:Reference Standards; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D011718:Pyrazinamide; C005296:pyrazinoic acid; C054996:5-hydroxypyrazinoic acid
keywords: 5-hydroxy pyrazinoic acid; Human plasma; LC–MS/MS; Pharmacokinetic study; Pyrazinamide; Pyrazinoic acid