Determination of famotidine in human plasma by high performance liquid chromatography with column switching.

A rapid, sensitive and robust reverse-phase high performance liquid chromatographic (HPLC) method with column switching and an internal standard for the quantitative determination of famotidine in human plasma is described. Famotidine and the internal standard were isolated from plasma samples by cation exchange solid phase extraction with SCX cartridges. The chromatographic separation was accomplished by an Inertsil C4 column with a mobile phase of acetonitrile/phosphate aqueous solution, connected by a switching valve to a BDS Hypersil C8 column with a mobile phase of acetonitrile/sodium dodecyl sulfate and phosphate aqueous solution. UV detection was set at 267 nm. The standard curve was linear in the concentration range of 1-100 ng ml-1. The intraday coefficients of variation at all concentration levels were less than 10%. The interday consistency was assessed by running QC samples during each daily run. The limit of quantification for famotidine in human plasma was 1 ng ml-1. The method has been utilized to support clinical pharmacokinetic studies in healthy volunteers who received famotidine 10 mg orally.