Development and validation of a stability indicating method for the enantioselective estimation of omeprazole enantiomers in the enteric-coated formulations by high-performance liquid chromatography

Omeprazole is widely prescribed in the form of enteric-coated formulations, due to the rapid degradation of the drug in the acidic condition of the stomach. In the current article, we are reporting the development and complete validation of a stability indicating chiral high-performance liquid chromatography (HPLC) method for the enantioselective analysis of omeprazole in the enteric-coated formulations. A precise and sensitive enantiomeric separation of omeprazole was obtained on Chiralcel OD-H analytical column (250mm × 4.6 mm, 5μm particle size) using normal phase chromatography. The analysis was performed under UV detection at 301nm wavelength. During method development, the addition of methanol to the mobile phase helped in getting the sharp peaks. The developed method showed linear response over a wide concentration range of 0.39-800μg/ml and the regression coefficients value (r(2)) was obtained more than 0.999 for (S)- and (R)-omeprazole. The lower limit of detection (LLOD) and lower limit of quantification (LLOQ) for (R)-omeprazole were found to be 0.39 and 0.78 μg/ml, respectively for 5 μl injection volume. The percentage recovery of (R)-omeprazole ranged from 93.5 to 104 in spiked formulation samples and omeprazole sample solution and mobile phase were found to be stable for at least 24 h at room temperature. The proposed method was found to be suitable and accurate for the quantitative determination of undesired enantiomer in the enteric-coated omeprazole formulations.