title: Determination of novel antibacterial triazolylmethyl oxazolidinones concentrations in human plasma by APCI-LC-MS: application to stability study.
abstract: Triazolylmethyl oxazolidinones are novel potent antibacterial agents recently synthesized in our laboratory.
  
  
  OBJECTIVE
  Development of a rapid and specific LC-MS method for evaluating the stability of three potentially active antibacterial triazolylmethyl oxazolidinone compounds, namely PH-27, PH-38 and PH-41, in human plasma.
  
  
  METHODS
  Ion-trap mass spectrometry using +APCI-MS at m/z 348.1 (PH-27), 389.1 (PH-38) and 451.1 (PH-41) combined with liquid chromatographic analysis using C18 reversed-phase column and a mobile phase consisting of 20 mM ammonium acetate solution and acetonitrile (50:50 v/v) was used. Plasma samples were pre-treated with acetonitrile to precipitate proteins prior to LC-MS analysis. Linezolid was used as an internal standard whose predominant ion at m/z 338.1 was monitored and used to construct the calibration curves. An accelerated stability study under controlled experimental conditions was conducted at -20 oC for a 5-weeks period.
  
  
  RESULTS
  Calibration curves of the examined oxazolidinones in human plasma were established (r: 0.99) up to the concentration of 20.0 microg ml-1 with LLQ of 0.1 (PH-27), 0.5 (PH-38) and 1.0 microg ml-1 (PH-41). Validation data showed appropriate intra- and inter-day precision and accuracy as indicated from RSD% 1.3 - 8.6 and % DEVs -12.7 to +11.3, respectively. Stability studies gave the kinetic degradation parameters of kdeg 0.0191- 0.0857 week-1, t1/2 8.1-36.3 weeks and t90 1.2 -5.5 weeks.
  
  
  CONCLUSIONS
  The developed +APCI-LC-MS assay is simple, fast and specific method that could be applied for the routine analysis of the selected oxazolidinones during stability and pharmacokinetic studies. The examined compound PH-27 was proved to be relatively more stable and resistant to degradation in human plasma compared to PH-38 and PH-41, as indicated from the kinetics and recovery studies at -20 oC.
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Kuwait University, Kuwait. dphillips@hsc.edu.kw
authors.forename: Oludotun A
authors.initials: OA
authors.lastname: Phillips
authors.forename: Mohammed E
authors.initials: ME
authors.lastname: Abdel-Hamid
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000900:Anti-Bacterial Agents / Q000097:blood* / Q000494:pharmacology; D002138:Calibration; D002853:Chromatography, Liquid; D002985:Clinical Protocols; D006801:Humans; D023303:Oxazolidinones / Q000097:blood* / Q000494:pharmacology; D015610:Serum Bactericidal Test; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods; D014230:Triazoles / Q000097:blood* / Q000494:pharmacology; D054928:Validation Studies as Topic
chemical_list: D000097:Acetonitriles; D000900:Anti-Bacterial Agents; D023303:Oxazolidinones; D014230:Triazoles; C032159:acetonitrile