title: Simultaneous determination of rifampicin and levofloxacin concentrations in catheter segments from a mouse model of a device-related infection by liquid chromatography/electrospray ionization tandem mass spectrometry.
abstract: The aim of this study was to develop a specific and sensitive liquid chromatography mass spectrometry (LC/MS) method for the determination of rifampicin and levofloxacin concentrations from infected tissues within teflon catheter segments which were subcutaneously implanted in mice. A solid-phase extraction procedure was used to extract analytes from tissue homogenates of the catheter segments and reverse-phase HPLC combined with positive electrospray ionization mass spectrometry was used for analyte separation and quantification. The assay was found to be linear over the concentration range of 0.02-2 microg/g for rifampicin and levofloxacin in tissues and provided good validation data for accuracy and precision. The intra-day accuracy as determined by the relative error was -1.3% for levofloxacin and 6.1% for rifampicin, and precision was evaluated by R.S.D.s with a maximum of 5.1% for levofloxacin and 8.1% for rifampicin. The inter-day accuracy was -3.3% for levofloxacin and -4.6% for rifampicin, and precision was 8.6% for levofloxacin and 7.1% for rifampicin. The assay uses less tissue than previously described methods and can be applied to determine the penetration of rifampicin and the fluoroquinolone in catheter segments from a mouse model of a device-related infection. Finally, the HPLC-MS assay should be applicable to studies of rifamycin+quinolone combination therapies in other animal models of bacterial infection.
authors.affiliation: Cumbre Pharmaceuticals Inc., 1502 Viceroy Drive, Dallas, TX 75235, USA. dbao@pharmasset.com
authors.forename: Donghui
authors.initials: D
authors.lastname: Bao
authors.forename: Thanh-Thai
authors.initials: TT
authors.lastname: Truong
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Renick
authors.forename: Mark E
authors.initials: ME
authors.lastname: Pulse
authors.forename: William J
authors.initials: WJ
authors.lastname: Weiss
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000032:analysis*; D002408:Catheters, Indwelling / Q000382:microbiology*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004195:Disease Models, Animal; D064704:Levofloxacin; D051379:Mice; D008807:Mice, Inbred BALB C; D015242:Ofloxacin / Q000032:analysis* / Q000494:pharmacology; D012293:Rifampin / Q000032:analysis* / Q000494:pharmacology; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013211:Staphylococcus aureus / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D064704:Levofloxacin; D015242:Ofloxacin; D012293:Rifampin