Spectrophotometric and chromatographic determination of omeprazole in pharmaceutical formulations

The purpose of this study was to determine the stability of the pH sensitive drug, omeprazole, within different solid oral pharmaceutical formulations and to determine whether the addition of antacid and surfactant agents, at varying concentrations, influenced drug stability and release. Spectrophotometric and chromatographic techniques were used for evaluation purposes, giving good results concerning linearity, precision and specificity within the range of concentrations used in this study. However, the results show that the degradation products of omeprazole interfere with spectrophotometric evaluation, making this technique insufficiently selective for omeprazole. On the other hand, liquid chromotography proved to be more sensitive, accurate and precise. Additionally, in an attempt to improve the administration form of the drug, an extemporaneous suspension was designed, which after evaluation proved to be a satisfactory administration vehicle. The best formulation of omeprazole studied is: omeprazole: 0.5%; corn starch 34.2%; aluminum hydroxide 26%; magnesium hydroxide 13%; simple syrup 24.8%; SDS 1%.