Development of a UPLC-MS/MS method for routine therapeutic drug monitoring of aripiprazole, amisulpride, olanzapine, paliperidone and ziprasidone with a discussion of their therapeutic reference ranges for Chinese patients.

A highly feasible and reliable ultra-high performance liquid chromatography tandem mass spectrometry method was presented for therapeutic drug monitoring of five anti-schizophrenic drugs (amisulpride, olanzapine, aripiprazole, paliperidone and ziprasidone) simultaneously. To meet the requirements of practical clinical usage (easy handling, high throughput and cost effectiveness), the pretreatment process was simplified (only including protein precipitation and mobile phase dilution steps) and the UPLC separation cycle was set within 6 min. The whole methodology was carefully validated according to the latest international guidelines showing the excellent selectivity, accuracy, precision, applicability and stability. After a 10 month clinical application, a retrospective analysis of 253 positive samples was carried out to investigate conformance with the Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie therapeutic reference range for Chinese patients. The results suggested good consistency for olanzapine, aripiprazole, paliperidone and ziprasidone, while for amisulpride, the plasma concentration level (445.2 ± 231.5 ng/mL) was relatively higher than the recommended range (100-320 ng/mL). We supposed that such phenomenon indicated the necessity of reconstructing a Chinese-specific therapeutic reference range for amisulpride treatment, which would be helpful to improve medication efficiency and safety for Chinese patients.