title: Simultaneous determination of moexipril and moexiprilat, its active metabolite, in human plasma by gas chromatography-negative-ion chemical ionization mass spectrometry.
abstract: A sensitive and selective method for the simultaneous determination of moexipril and moexiprilat, its active metabolite, in human plasma is described using quinapril and quinaprilat as internal standards. The analytes are isolated from human plasma by means of Bond Elut C18 cartridges, methylated with diazomethane, purified by acid-base partitioning and converted to the corresponding trifluoroacetamides using trifluoroacetic anhydride. Moexipril and moexiprilat were analysed by gas chromatography-negative-ion chemical ionization mass spectrometry (GC-NICI-MS) at the fragment ions m/z 302 and m/z 288, respectively. The lower limit of quantitation both for moexipril and moexiprilat is 0.5 ng/ml of human plasma. Linear calibration curves are obtained over the concentration range 0.5-300 ng/ml of human plasma. In any case the imprecision and the inaccuracy are < 15%. The present method has been successfully applied to various pharmacokinetic studies in human subjects and patients.
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000097:blood* / Q000493:pharmacokinetics; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D007546:Isoquinolines / Q000097:blood* / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D044005:Tetrahydroisoquinolines
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D007546:Isoquinolines; D044005:Tetrahydroisoquinolines; C059506:moexiprilat; C058302:moexipril