Spectrophotometric and chromatographic determination of omeprazole in pharmaceutical formulations

Abstract

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%.

An amplified electrochemical sensor employing one-step synthesized nickel–copper–zinc ferrite/carboxymethyl cellulose/graphene oxide nanosheets composite for sensitive analysis of omeprazole

“…87 This result is consistent with the electrochemical oxidation mechanism of OMP that shown in Scheme S2 †. 83,84 On the other hand, the electrochemical oxidation mechanism of OMP involves the removal of an electron and the formation of an intermediate cation radical. Then deprotonation occurs, aer which the radical cation reacts with water molecules and nally leads to the production of an irreversible hydroxylated product.…”

“…Based on the obtained results and according to the literature reported for OMP oxidation, the suggested electrooxidation mechanism of OMP can be expressed as Scheme S2, † in which the number of electrons and protons is 1. 21,22,83,84 From the chemical point, OMP is a weak lipophilic base with pK a1 = 4.2 and pK a2 = 9 and decomposes unless protected against acidic conditions. 85,86 Based on the values of pK a for OMP, at the pHs lower than the pK a1 , due to the protonation of OMP molecule, its oxidation process may be more difficult and therefore the current should increase with increasing pH around its pK a1 .…”

Precision improvement for omeprazole determination through stability evaluation

“…Some reported analyses for OMP solutions,9–18 including the USP 26 official method,13 mainly use UV detection systems and involve previous separation methods like HPLC or liquid‐liquid extraction, which take between 15 and 20 min for each injection or extraction step for each sample and standard. The rapid decomposition of the drug in solution, even when only exposed to natural light, suggests that the UV absorbance measurements in these methods may not be accurate and precise, since there is a gap of several minutes between the sample/standard preparation and the instrumental detection.…”

“…OMP has been determined in formulations through a variety of methods, such as spectrophotometry,9–11 chromatography,12, 13 micellar electrokinetic capillary chromatography,14 and non‐aqueous capillary electrophoresis 15. Shaghaghi et al described a first attempt to indirectly determine OMP in capsules by spectrofluorimetry.…”

Formulation of Dosage Forms with Proton Pump Inhibitors: State of the Art, Challenges and Future Perspectives

“…Some of them show absorbance in similar range as initial compound, thus, employment of separation techniques may be necessary. Therefore, besides spectrophotometry, also high performance and ultra-high performance liquid chromatography (HPLC and UPLC) are commonly used to identify PPIs and their degradation products or to measure the concentration of PPIs in pharmaceutical formulations or biological samples [ 56 , 57 ] ( Table 2 ).…”