title: Selective and sensitive determination of amisulpride in human plasma by liquid chromatography-tandem mass spectrometry with positive electrospray ionisation and multiple reaction monitoring.
abstract: The development of a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method with positive electrospray ionisation (ESI(+)) and multiple reaction monitoring (MRM) for the selective and sensitive bioanalytical determination of amisulpride, a substituted benzamide derivative, in human plasma is described. Plasma was cleaned up using a liquid-liquid extraction (diisopropylether:dichloromethane=1:1 (v/v)) procedure. The chemically related drug sulpiride was used as internal standard (ISTD) and a primary calibration function was established in the concentration range of 0.50-500.52 ng/ml for amisulpride in plasma by triple analysis of the corresponding calibration standards. A linear relationship between concentration and signal intensity (given as peak area ratio analyte/ISTD) was obtained (linear regression: r=0.9999). A lower limit of quantification (LLQ) of 0.50 ng/ml was used during measurement of study plasma samples. Satisfying results of within-day precision (CV=0.79 to 1.98%) and accuracy (mean relative deviation: -1.68 to 3.58%) and between-day precision (CV=1.34 to 4.62%) and accuracy (mean relative deviation: -1.73 to -3.77%) as well as of recovery (amisulpride: 81.74 to 84.83%; sulpiride: 58.65%) and selectivity investigations confirmed the high reliability of this established LC-MS/MS method. Sufficient stability of amisulpride in plasma was achieved during freeze-thaw-cycles, for storage periods of 24h at room temperature and 20 days at <-20 degrees C as well as in extracts (storage conditions: <-20 degrees C, 6 days and 7 degrees C, 6 days) with mean relative deviations between - 2.83 and 2.91%. An example of a pharmacokinetic profile determined after administration of an amisulpride 200mg dose in a pilot study is given in this paper. A peak plasma concentration (C(max)) of 522.58 ng/ml was achieved after 3.55 h (t(max)). Corresponding values of areas under the plasma concentration-time curve (AUC) of 3405.35 ngh/ml (AUC(0-infinity)) and 3306.54 ngh/ml (AUC(0-tlast)) were obtained. The terminal plasma elimination half-life (t(1/2)) was 10.36 h.
authors.affiliation: Pharmakin GmbH, Gesellschaft für Pharmakokinetik, Graf-Arco-Strasse 3, 89079 Ulm, Germany. michael.gschwend@pharmakin.de
authors.forename: M H
authors.initials: MH
authors.lastname: Gschwend
authors.forename: P
authors.initials: P
authors.lastname: Arnold
authors.forename: J
authors.initials: J
authors.lastname: Ring
authors.forename: W
authors.initials: W
authors.lastname: Martin
mesh_terms: D000077582:Amisulpride; D002853:Chromatography, Liquid / Q000379:methods*; D004355:Drug Stability; D006801:Humans; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013469:Sulpiride / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics
chemical_list: D013469:Sulpiride; D000077582:Amisulpride