title: Determination of famotidine in low-volume human plasma by normal-phase liquid chromatography/tandem mass spectrometry.
abstract: A rapid, sensitive and robust assay procedure using liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) for the determination of famotidine in human plasma and urine is described. Famotidine and the internal standard were isolated from plasma samples by cation-exchange solid-phase extraction with benzenesulfonic acid (SCX) cartridges. The urine assay used direct injection of a diluted urine sample. The chromatographic separation was accomplished by using a BDS Hypersil silica column with a mobile phase of acetonitrile-water containing trifluoroacetic acid. The MS/MS detection of the analytes was set in the positive ionization mode using electrospray ionization for sample introduction. The analyte and internal standard precursor-product ion combinations were monitored in the multiple-reaction monitoring mode. Assay calibration curves were linear in the concentration range 0.5--500 ng ml(-1) and 0.05--50 microg ml(-1) in plasma and urine, respectively. For the plasma assay, a 100 microl sample aliquot was subjected to extraction. To perform the urine assay, a 50 microl sample aliquot was used. The intra-day relative standard deviations at all concentration levels were <10%. The inter-day consistency was assessed by running quality control samples during each daily run. The limit of quantification was 0.5 ng ml(-1) in plasma and 0.05 microg ml(-1) in urine. The methods were utilized to support clinical pharmacokinetic studies in infants aged 0-12 months.
authors.affiliation: Department of Drug Metabolism, Merck Research Laboratories, West Point, Pennsylvania 19486, USA. ling_zhong@merck.com
authors.forename: L
authors.initials: L
authors.lastname: Zhong
authors.forename: R
authors.initials: R
authors.lastname: Eisenhandler
authors.forename: K C
authors.initials: KC
authors.lastname: Yeh
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D015738:Famotidine / Q000097:blood* / Q000493:pharmacokinetics / Q000652:urine; D006635:Histamine H2 Antagonists / Q000097:blood* / Q000493:pharmacokinetics / Q000652:urine; D006801:Humans; D007202:Indicators and Reagents; D007223:Infant; D007231:Infant, Newborn; D013058:Mass Spectrometry / Q000379:methods*; D011786:Quality Control; D012680:Sensitivity and Specificity; D014269:Trifluoroacetic Acid
chemical_list: D006635:Histamine H2 Antagonists; D007202:Indicators and Reagents; D015738:Famotidine; D014269:Trifluoroacetic Acid