Determination of famotidine in human plasma and urine by high-performance liquid chromatography

An improved, rapid and specific high-performance liquid chromatographic assay was developed for the determination of famotidine in human plasma and urine. Plasma samples were alkalinized and the analyte and internal standard (cimetidine) extracted with water-saturated ethyl acetate, The extracts were reconstituted in mobile phase, and injected onto a C-18 reversed-phase column; UV detection was set at 267 nm. Urine samples were diluted with nine volumes of a mobile phase-internal standard mixture prior to injection. The lower limits of quantification in plasma and urine were 75 ng/ml and 1.0 mu g/ml, respectively; intra- and inter-day coefficients of variation were less than or equal to 10.5%. This method is currently being used to support renal function studies assessing the use of intravenously administered famotidine to characterize cationic tubular secretion in man. (C) 1999 Elsevier Science B.V. All rights reserved.