Simultaneous Determination of Olanzapine and its Major Metabolite N-Desmethyl Olanzapine in Rat Plasma by HPLC-MS/MS: Application of PK in Rat

Abstract

Despite this importance, there havebeen no reports about the simultaneous determination ofOLZ and N-DMO concentrations in rat plasma by HPLC-MS/MS. This study describes a simple and rapid method forthe simultaneous determination of OLZ and N-DMO in ratplasma by HPLC-MS/MS with electrospray ionization, aftersample pretreatment by deproteinization with methanol. OLZ and N-DMO were purchased from Waterstone Techno-logy (Carmel, IN, USA) and Toronto Research Chemicals,Inc. (North York, Ontario, Canada), respectively. Carbama-zepine, used as an internal standard (IS), was purchasedfrom Sigma-Aldrich Canada Co. (Oakville, Ontario, Canada).HPLC-grade methanol was from Merck (Darmstadt, Ger-many). LC was performed on an Agilent 1100 HPLC system(Agilent technologies, Inc., Santa Clara, CA, USA). PE SCIEXAPI 2000 triple quadrupole mass spectrometer (AppliedBiosystems, Foster City, CA, USA) were used as a detectorStock solutions (1 mg/mL) of OLZ and N-DMO werediluted serially with methanol. To optimize MS conditions, asolution of containing 100 ng/mL of OLZ or N-DMO wasinfused into the mass spectrometer at a flow rate of 10 μL/min. The precursor ions for the analytes were optimized asprotonated molecular ions, [M+H]