Validated LC-MS/MS Method for Simultaneous Determination of Aripiprazole and its Three Metabolites in Human Plasma

Aripiprazole, a partial agonist of dopamine D-2 receptors, is primarily metabolized to active dehydroaripiprazole and then converted to its urinary metabolites 1-(2,3-dichlorophenyl) piperazine (DCPP) and 3,4-dihydro-7-(3'carboxy) propoxy-2(1H) quinolinone (DCPQ). This study aimed to develop a simultaneous determination method for aripiprazole and its three metabolites in human plasma using isocratic liquid chromatography coupled to tandem mass spectrometry and then to apply it to pharmacokinetic analyses. The pretreatments for human plasma involve protein precipitation using acetonitrile under basic conditions. Aripiprazole and its metabolites were separated on an octadecylsilyl column filled with 3-A mu m particles using an isocratic mixture of 30% acetonitrile containing 0.1% formic acid with a total run time of 10 min. The mass spectrometer was run in the positive ion multiple reaction monitoring mode. The calibration curves were linear over the plasma concentration ranges 2-2000 ng mL(-1) for aripiprazole, and 1-1000 ng mL(-1) for dehydroaripiprazole, DCPP, and DCPQ. The lower limits of quantification in human plasma were 2 ng mL(-1) for aripiprazole and 1 ng mL(-1) for the metabolites. Their pretreatment recoveries were 88.3-102.7%. The intra-assay precision and accuracy were within 1.7-9.6 and 86.9-105.9% and inter-assay precision and accuracy were within 3.1-9.1 and 87.4-102.4%, respectively. The plasma concentrations of aripiprazole, dehydroaripiprazole, DCPP, and DCPQ ranged from 42.8 to 1369, 1.01-548, 1.02-46.1, and 1.69-475 ng mL(-1), respectively, in 20 schizophrenia patients. In conclusion, this simultaneous determination method with acceptable analytical performance can be helpful for evaluating the pharmacokinetics of aripiprazole including the determination of its metabolites, in clinical research.