Determination of gentamicin in different matrices by a new sensitive high-performance liquid chromatography-mass spectrometric method.
OBJECTIVE
The aim of this work was to develop and validate an HPLC method for gentamicin quantification in different types of biological samples such as animal tissues and cellular material and also in pharmaceuticals.


METHODS
Poly(lactide-co-glycolide) microparticles (MP) of gentamicin (PLGA 502H MP), THP-1 cells, and plasma and tissue samples of mice treated with the antibiotic either free or loaded into PLGA 502H MP were processed by a simple preparation procedure, subjected to chromatography on a reversed-phase column and measured by mass spectrometry detection. The developed method was compared with bioassay and fluorimetric assay methods previously used for gentamicin determination.


RESULTS
The HPLC method was linear over the ranges 40-800 ng/mL and 0.1-100 microg/mL and showed good accuracy (average accuracy < 5.59%) and reproducibility (CV < 6.13%). Encapsulation of gentamicin in PLGA 502H MP was determined by the three methods. Good correlation was observed between bioassay (reference method) and HPLC. Extra- and intracellular in vitro antibiotic accumulation was determined by bioassay and chromatography. Both methods gave similar extracellular concentrations but the HPLC-MS technique demonstrated an improved accuracy (5.59% versus 14%) and precision (6.13% versus 15%) compared with bioassay. However, only the HPLC-MS method was sensitive enough to detect the drug, intracellularly and in tissues.


CONCLUSIONS
All these data favour the use of chromatography-mass spectrometry as a versatile technique not only suitable for gentamicin quantification loaded in drug delivery systems, but also sensitive and specific enough for in vivo and intracellular studies.
Lecároz
Concepción
C
Department of Microbiology, University of Navarra, Pamplona, Spain.
Campanero
Miguel A
MA
Gamazo
Carlos
C
Blanco-Prieto
María J
MJ
D000818:Animals; D000900:Anti-Bacterial Agents / Q000032:analysis* / Q000097:blood / Q000493:pharmacokinetics*; D001681:Biological Assay; D002138:Calibration; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005839:Gentamicins / Q000032:analysis* / Q000097:blood / Q000493:pharmacokinetics*; D006801:Humans; D016014:Linear Models; D013058:Mass Spectrometry; D051379:Mice; D008807:Mice, Inbred BALB C; D008863:Microspheres; D009000:Monocytes / Q000378:metabolism; D004364:Pharmaceutical Preparations / Q000032:analysis / Q000592:standards; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence; D014018:Tissue Distribution
D000900:Anti-Bacterial Agents; D005839:Gentamicins; D004364:Pharmaceutical Preparations