Comparison of two high-performance liquid chromatographic methods for the determination of oxmetidine and its metabolites in plasma, bile and urine samples.

Two high-performance liquid chromatographic methods for the assay of oxmetidine are described: both utilize the same liquid extraction from plasma, urine and bile samples. A normal-phase technique is considered most suitable for the analysis of plasma extracts and a reversed-phase method is preferred for the assay of excretory fluids such as urine and bile which will contain polar metabolites in detectable quantity as well as unchanged oxmetidine The methods are sensitive enough to follow the kinetic changes in concentration for up to 8 h after the administration of recommended therapeutic doses. Both methods can be automated in respect of the high-performance liquid chromatograph and the samples can be stored for several weeks at -20 degrees C without prejudicing the accuracy of the analysis.