Simple and robust high-performance liquid chromatographic method for the determination of ranitidine in microvolumes...

A simple robust high-performance liquid chromatographic method is described for the determination of ranitidine in microvolumes of human serum. The drug of interest was isolated using liquid-liquid extraction with dichloromethane and back-extraction with 0.1% phosphoric acid and separation was obtained using a reversed-phase column under isocratic conditions, with ultraviolet detection at 313 nm. Intra-day and inter-day coefficients of variation ranged from 1 to 6% and 3 to 10%, respectively. Accuracy of the assay was less than 10% at all concentrations. The limit of detection and the limit of quantitation were 2 and 7 ng/ml, respectively. The linearity was assessed in the range 10-1000 ng/ml. It was shown that a group of common drugs co-administered with ranitidine did not interfere with its determination. The applicability of this method for the pharmacokinetic study of ranitidine following i.v. infusion in patients was demonstrated using only 100 microl of serum. The ruggedness of the assay was demonstrated over a three-year period.