A simple and sensitive bioanalytical assay for simultaneous determination of omeprazole and its three major metabolites in human blood plasma using RP-HPLC after a simple liquid-liquid extraction procedure.

A simple, sensitive and specific reverse-phase high-performance liquid chromatography (HPLC) assay for the simultaneous quantitative determination of omeprazole and its three metabolites in human plasma was developed and validated. This method provides excellent chromatographic resolution and peak shape for the four components and the internal standard within a 17 min run time. The simple extraction method results in a clean base line and relatively high extraction efficiency. The method was validated over the range of 2-2000 ng/mL, with 2.0 ng/mL as the lower limit of quantification. Within- and between-day accuracies for five different concentrations ranged from 95 to 102%, and 95 to 114%, respectively. Within- and between-day precision ranged from 1.1 to 6.3% and 0.5 to 6.2%, respectively. Simplicity and high throughput make this method suitable for clinical pharmacokinetic studies.