title: Interference from a glucuronide metabolite in the determination of ramipril and ramiprilat in human plasma and urine by gas chromatography-mass spectrometry.
abstract: In the course of development and validation of a gas chromatography-mass spectrometry (GC-MS) method for ramipril and its biologically active metabolite ramiprilat, evidence was found for an unknown interfering metabolite. Sample treatment included isolation from plasma or urine by solid-phase extraction, methylation with trimethylsilyldiazomethane and acylation with trifluoroacetic anhydride (TFAA). When liquid chromatography was used to fractionate plasma extracts prior to derivatization, the alkyl, acyl-derivative of ramipril was obtained from two separate LC fractions. Electrospray ionization mass spectral data, together with circumstances for the derivatization, were consistent with the presence of an N-glucuronide of ramipril. Interference from the metabolite was eliminated by including a wash step after extraction/alkylation, prior to acylation. The final assay had a lower limit of quantification at 1.0 nmol/L and a linear range of 1-300 nmol/L. Intra- and inter-batch precision for ramipril and ramiprilat in plasma or urine were better than 10 and 5% at 2 and 80 nmol/L, respectively.
authors.affiliation: DMPK & Bioanalytical Chemistry, AstraZeneca R&D Mölndal, SE-431 83 Mölndal, Sweden. bengt-arne.persson@astrazeneca.com
authors.forename: Bengt-Arne
authors.initials: BA
authors.lastname: Persson
authors.forename: Christina
authors.initials: C
authors.lastname: Fakt
authors.forename: Magnar
authors.initials: M
authors.lastname: Ervik
authors.forename: Martin
authors.initials: M
authors.lastname: Ahnoff
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000097:blood* / Q000652:urine*; D002138:Calibration; D008401:Gas Chromatography-Mass Spectrometry; D020719:Glucuronides / Q000097:blood / Q000652:urine; D006801:Humans; D007202:Indicators and Reagents; D013058:Mass Spectrometry; D008745:Methylation; D017257:Ramipril / Q000031:analogs & derivatives* / Q000097:blood / Q000652:urine; D012015:Reference Standards; D015203:Reproducibility of Results
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D020719:Glucuronides; D007202:Indicators and Reagents; C052549:ramiprilat; D017257:Ramipril