title: Rapid analysis of metabolic stability of dopamine receptor antagonists and detection of their metabolites by liquid chromatography/tandem mass spectrometry.
abstract: In vitro metabolic stability of dopamine D(3)/D(4) receptor antagonists and identification of their metabolites by high-performance liquid chromatography (HPLC) coupled with ion-trap mass spectrometry (ITMS) were assessed in rat liver microsomes. The compounds were divided into three cassette groups for rapid quantitative analysis of multiple drugs and simultaneous detection of their metabolites. The samples from incubation with rat liver microsomes were pooled into designed cassette groups and analyzed by HPLC/electrospray ITMS in full-scan mode. The metabolic stability of the drugs was determined by comparing their signals after incubation for 0 and for 30min. The metabolic stability of the examined dopamine receptor antagonists was in the range of 9.9-84.4%. In addition, the present cassette analysis allowed the simultaneous detection of metabolites formed during the same incubation without having to reanalyze the samples. The metabolites were first characterized by nominal mass measurement of the corresponding protonated molecules. Subsequent multistage tandem mass spectrometry on the ion-trap instrument allowed characterization of the structure of the detected metabolites. N,O-dealkylation and ring hydroxylation reactions were identified as major metabolic reactions in piperazinylalkylisoxazole derivatives. These results suggested that the present approach is useful for the rapid evaluation of metabolic stability and structural characterization of metabolites within a short period in new drug discovery.
authors.affiliation: Bioanalysis and Biotransformation Research Center, Korea Institute of Science and Technology, P.O. Box 131, Chungryang, Seoul, South Korea.
authors.forename: Jaeick
authors.initials: J
authors.lastname: Lee
authors.forename: Junghyun
authors.initials: J
authors.lastname: Son
authors.forename: Hun
authors.initials: H
authors.lastname: Yeoung Koh
authors.forename: Ae
authors.initials: A
authors.lastname: Nim Pae
authors.forename: Dong-Hyun
authors.initials: DH
authors.lastname: Kim
mesh_terms: D000478:Alkylation; D000818:Animals; D002853:Chromatography, Liquid / Q000379:methods; D018492:Dopamine Antagonists / Q000032:analysis* / Q000378:metabolism*; D065127:Dopamine D2 Receptor Antagonists; D004355:Drug Stability; D006900:Hydroxylation; D013058:Mass Spectrometry / Q000379:methods; D008862:Microsomes, Liver / Q000378:metabolism; D010879:Piperazines / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D050637:Receptors, Dopamine D3; D050638:Receptors, Dopamine D4
chemical_list: D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; C493595:Drd3 protein, rat; C493601:Drd4 protein, rat; D010879:Piperazines; D050637:Receptors, Dopamine D3; D050638:Receptors, Dopamine D4