a Biopharmacy Division, Faculty of Pharmacy, Tehran University of Medical Sciences, 14155/6451, Tehran, Iran
b Biopharmacy Division, Faculty of Pharmacy, Shaheed Beheshti University of Medical Sciences, Tehran, Iran
Abstract:
A simple and highly selective isocratic high-performance liquid chromatography method is presented for the simultaneous determination of theophylline and its major metabolites in human urine using β-hydroxyethyl theophylline as an internal standard. The method utilizes direct injection of diluted urine samples followed by separation and quantitation by reversed-phase isocratic elution and ultraviolet detection. The assay is accurate and reproducible with a sensitivity of 1 μg ml?1 for theophylline and 0.5 μg ml?1 for its metabolites. The assay was employed for the analysis of theophylline and its major metabolites in urine following the oral administration of theophylline to four healthy volunteers.