A novel, rapid and selective ultra performance liquid chromatography mass spectrometric method had been developed for the pharmacokinetic study of diclofenac sodium (DS) after single intravenous injection of DS aqueous injection and DS lipid microsphere (LM) injection in rats. Ketoprofen (KP) was used as internal standard. Samples were treated by a one-step liquid liquid extraction. Separation was performed on an Acquity UPLC BEH C(18) column (50 x 2.1 mm i.d., 1.7 mum). The mobile phase consisted of acetonitrile-0.1% ammonium hydroxide aqueous solution (20 : 80, v/v) initially in the gradient mode. The detection was carried out by means of electrospray ionization mass spectrometry in negative ion mode with multiple-reaction monitoring mode. Standard curves showed good linearity (r > 0.99) from the plasma concentration of 0.1-50 microg/mL. The lower limit of quantification was 0.1 microg/mL. The intra- and inter-day precisions and the accuracy all satisfied the acceptance criteria. The developed method was validated and successfully applied to the pharmacokinetics study of DS aqueous injection and LM injection. The results showed that the two preparations were bioequivalent in rats.
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