title: Validation and clinical application of an LC-ESI-MS/MS method for simultaneous determination of tolmetin and MED5, the metabolites of amtolmetin guacil in human plasma.
abstract: A highly sensitive, rapid assay method has been developed and validated for the simultaneous estimation of tolmetin (TMT) and MED5 in human plasma with liquid chromatography coupled to tandem mass spectrometry with electrospray ionization in the positive-ion mode. A simple solid-phase extraction process was used to extract TMT and MED5 along with mycophenolic acid (internal standard, IS) from human plasma. Chromatographic separation was achieved with 0.2% formic acid-acetonitrile (25:75, v/v) at a flow rate of 0.50 mL/min on an X-Terra RP(18) column with a total run time of 2.5 min. The MS/MS ion transitions monitored were 258.1 → 119.0 for TMT, 315.1 → 119.0 for MED5 and 321.2 → 207.0 for IS. Method validation and clinical sample analysis were performed as per FDA guidelines and the results met the acceptance criteria. The lower limit of quantitation achieved was 20 ng/mL and the linearity was observed from 20 to 2000 ng/mL, for both the anlaytes. The intra-day and inter-day precisions were in the range 3.27-4.50 and 5.32-8.18%, respectively for TMT and 4.27-5.68 and 5.32-8.85%, respectively for MED5. This novel method has been applied to a clinical pharmacokinetic study.
authors.affiliation: Bioanalytical Department, Integrated Product Development, Dr Reddy's Laboratories Ltd, Bachupalli, Hyderabad-500 072, India.
authors.forename: Kishore Kumar
authors.initials: KK
authors.lastname: Hotha
authors.forename: D Vijaya
authors.initials: DV
authors.lastname: Bharathi
authors.forename: S Sirish
authors.initials: SS
authors.lastname: Kumar
authors.forename: Y Narsimha
authors.initials: YN
authors.lastname: Reddy
authors.forename: Pankaj
authors.initials: P
authors.lastname: Chatki
authors.forename: L K
authors.initials: LK
authors.lastname: Ravindranath
authors.forename: K N Jaya
authors.initials: KN
authors.lastname: Veera
authors.forename: Ramesh
authors.initials: R
authors.lastname: Mullangi
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods*; D004355:Drug Stability; D005998:Glycine / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry / Q000493:pharmacokinetics; D006801:Humans; D016014:Linear Models; D008297:Male; D011758:Pyrroles / Q000737:chemistry / Q000493:pharmacokinetics*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014046:Tolmetin / Q000031:analogs & derivatives* / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics
chemical_list: C554752:1-methyl-5-p-methylbenzoylpyrrol-2-acetamidoacetic acid; D011758:Pyrroles; C065762:ST 679; D014046:Tolmetin; D005998:Glycine