Improved Method for the Determination of Cimetidine in Human Serum by High - Performance Liquid Chromatography

Abstract

A simple and reproducible method for the determination of [the antiulcer drug] cimetidine in serum was described. Separation and quantitation were performed by high-performance liquid chromatography using a Radial-Pak Cn column with a mobile phase of 33% acetonitrile solution containing 5 mM triethylamine (adjusted to pH 3.0 with phosphoric acid) at a flow rate of 2 ml/min and at a detection of 220 nm. Cimetidine and ranitidine as an internal standard were extracted from serum with ethyl acetate and then back-extracted into dilute acid. An aliquot of the dilute acid was analyzed in the chromatographic system. The limit of detection was as low as 0.02 .mu.g/ml using 100 .mu.l serum at a signal-to-noise ratio of 2. Recoveries of cimetidine and ranitidine from serum were > 95%. Within-run and day-to-day reproducibility for 10.0 .mu.g/ml samples were 2.6 and 2.9%, respectively. The method was applicable to pharmacokinetic studies.