High-performance liquid chromatographic methods for the determination of ranitidine and its metabolites in biological fluids

Abstract

The use of an existing reversed-phase ion-pair method for the determination of ranitidine, ranitidine-N-oxide, ranitidine-S-oxide and desmethylranitidine in the plasma of patients taking the anti-ulcer drug, ranitidine is described. The development of a ternary reversed-phase system which is more suitable for the routine determination of ranitidine and the three metabolites is reported. This system has been used to determine quantitatively ranitidine and the metabolites in urine. Studies in animals using14C-ranitidine have shown that ranitidine is also oxidatively deaminated to a 5-substituted, 2-furan carboxylic acid. A reversed-phase ion-pair system, in which cetrimide is the counter ion, has been developed for the quantitative determination of the 5-substituted, 2-furan carboxylic acid and ranitidine-N-oxide in urine and faeces from patients treated with ranitidine.