Determination of ranitidine and its metabolites in human urine by reversed-phase ion-pair high-performance liquid chromatography.

A method using ion-pair high-performance liquid chromatography is presented for determining ranitidine, ranitidine N-oxide, ranitidine S-oxide and desmethyl ranitidine in the urine from four volunteers, given on separate occasions an intravenous and oral dose of 100 mg ranitidine. This method has been used to study the metabolism and pharmacokinetics of ranitidine by man. It was found that the elimination half-life of ranitidine ranged from 110-246 min. The mean renal clearance of ranitidine in these four volunteers was 512 ml/min.