Validation of a simplified method for determination of cimetidine in human plasma and urine by liquid chromatography with ultraviolet detection

A HPLC method was developed for determination of cimetidine in human plasma and urine. Plasma samples were alkalinized followed by liquid extraction with water-saturated ethyl acetate then evaporated under nitrogen. The extracts were reconstituted in mobile phase and injected onto a C 18 reversed-phase column; UV detection was set at 228 nm. Urine samples were diluted with an internal standard/mobile phase mixture (1:9) prior to injection. The lower limit of quantification in plasma and urine were 100 ng/ml and 10 mug/ml, respectively-, intraand inter-day coefficients of variation were less than or equal to4.2%. Advantages of this validated assay include a readily available internal standard, simplified plasma extraction and urine dilution methods, and applicability to clinical studies investigating the renal handling of cimetidine. (C) 2003 Elsevier B.V All rights reserved.