LC–ESI-MS determination and pharmacokinetics of adrafinil in rats

A highly sensitive and specific liquid chromatography/tandem mass spectrometric (LC–MS/MS) method for investigating the pharmacokinetics of adrafinil in rats was developed. Rat serum pretreated by solid-phase extraction (SPE) was analyzed by LC–MS/MS with an electrospray ionization (ESI) interface. The mobile phase consisted of acetonitrile:water:acetic acid (35:65:0.1, v/v/v) in an isocratic elution mode pumped at 1.0 ml/min. The analytical column (250 mm × 4.6 mm i.d.) was packed with Kromasil C18 material (5.0 μm). The standard curve was linear from 16.5 to 5000 ng/ml. The assay was specific, accurate (R.S.D. < 2.6%), precise and reproducible (within- and between-day precisions R.S.D. <7.0% and <9.0%, respectively). Adrafinil in rat serum was stable over three freeze–thaw cycles at ambient temperature for 6 h. The method had a lower limit of quantitation of 16.5 ng/ml, which offered high sensitivity for the determination of adrafinil in serum. The method was successfully applied to pharmacokinetic studies of adrafinil after an oral administration to rats.