Sensitive and selective liquid chromatography–tandem mass spectrometry method for the quantification of aniracetam in human plasma

A rapid, sensitive and selective LC–MS/MS method was developed and validated for the quantification of aniracetam in human plasma using estazolam as internal standard (IS). Following liquid–liquid extraction, the analytes were separated using a mobile phase of methanol–water (60:40, v/v) on a reverse phase C18 column and analyzed by a triple-quadrupole mass spectrometer in the selected reaction monitoring (SRM) mode using the respective [M + H]+ ions, m/z 220 → 135 for aniracetam and m/z 295 → 205 for the IS. The assay exhibited a linear dynamic range of 0.2–100 ng/mL for aniracetam in human plasma. The lower limit of quantification (LLOQ) was 0.2 ng/mL with a relative standard deviation of less than 15%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The validated LC–MS/MS method has been successfully applied to study the pharmacokinetics of aniracetam in healthy male Chinese volunteers.