Determination of omeprazole in rat plasma by high-performance liquid chromatography without solvent extraction

A HPLC method without solvent extraction and using ultraviolet detection at 302 nm for the determination of omeprazole in rat plasma has been validated. Plasma samples after pretreatment with acetonitrile to effect deproteinization were dried under N2 at 40 °C and reconstituted with mobile phase. The standard calibration curve for omeprazole was linear (r2 = 0.9999) over the concentration range of 0.02–3 μg ml−1. The intra- and inter-day assay variability range was 4.8–9.2% and 5.2–10.3% individually. This method has been successfully applied to a pharmacokinetic study of omeprazole in rats.