Abstract

Determination and pharmacokinetics of diclofenac in rabbit plasma by gas chromatography with mass spectrometry

Author(s): Bilal Yilmaz, Vedat Akba

This paper describes a gas chromatography-mass spectrophotometry (GCMS) method for determination of diclofenac in rabbit plasma. Diclofenac and internal standard (IS) naproxen were extracted by liquid-liquid extraction method. The samples were separated by GC on a DB-5MS analytical column and determined by a quadrupole mass spectrometer detector operated under selected ion monitoring mode (SIM). Excellent linearity was found between 5 and 600ng mL-1 (r=0.999) for plasma samples. Intra-day and inter-day precisions expressed as the relative standard deviation (RSD) for themethodwere 2.13-3.21%and 4.62-5.83%, respectively. The recoveries for all samples were >92.3%. This assay was successfully applied to a pharmacokinetic study of diclofenac in New Zealand white rabbits. As a result, the plasma half-life was 65.8 ± 16.27 min and the mean AUC0-360 min was 5841.8 ± 1382.8 min ng mL-1. Themaximumplasma concentration (Cmax) of 587.1 ± 74.21ng mL-1 reached 45.0 ± 13.41 min after administration.