Precision improvement for omeprazole determination through stability evaluation.

A new spectrofluorimetric method for the determination of omeprazole (OMP) based on its degradation reaction catalyzed by ultraviolet (UV) light is proposed. OMP in aqueous solution is very unstable, which renders a serious difficulty for controlling its quality. It does not show native fluorescence, but when exposed to UV radiation, it generates a highly fluorescent degradation product with adequate stability for indirect OMP quantification. Under the studied optimal experimental conditions (pH, temperature, exposure time to UV radiation), a specific rate constant of 2.851 min⁻¹--described by zero-order kinetic--was obtained for the degradation reaction. Using λ(exc) 293 nm and λ(em) 317 nm, a linear relationship was obtained (r² 0.9998) in the concentration range of 0.1 to 1.3 µg mL⁻¹, with a detection limit of 1.07 10⁻³ µg mL⁻¹ (S/N = 3). The methodology developed was successfully applied to OMP quality control in pure drugs and tablet dosage forms without previous treatment, with good tolerance to common excipient, and a high level of concordance between the nominal and experimental values. This work constitutes an important contribution to knowledge of the degradation mechanism of OMP. It has been shown to be appropriate for OMP quality control, to have an adequate sampling rate, low cost instrument, and to be a less polluting procedure.

Stability and viscosity of a flavored omeprazole oral suspension for pediatric use.

PURPOSE: The stability and viscosity of preparations of a commercially available, flavored, immediate-release powder for oral suspension (omeprazole-sodium bicarbonate) during refrigerator and room temperature storage were investigated. METHODS: Omeprazole-sodium bicarbonate 20-mg packets were suspended to initial omeprazole concentrations of 0.6 and 2 mg/mL, and omeprazole-sodium bicarbonate 40-mg packets were suspended to initial omeprazole concentrations of 1.2, 2, 3, and 4 mg/mL. Suspensions were stored at 4 degrees C in darkness (refrigerated) or 22-25 degrees C (room temperature) in light for one week. A third set of suspensions was stored refrigerated for one month. Omeprazole's stability was quantified after 0, 6, 12, 24, 48, and 168 hours in one-week samples and after 0, 7, 14, 21, and 28 days in one-month samples using high-pressure liquid chromatography. Viscosities of refrigerated suspensions were measured after 0, 1, and 7 days. RESULTS: Refrigerated suspensions retained >98% and >96% of their initial omeprazole concentrations after one week and one month, respectively. Stability of room temperature suspensions was concentration dependent. After one week, the 0.6- and 1.2-mg/mL suspensions retained 87.2% and 93.1% of their respective initial omeprazole concentrations, whereas the 2-, 3-, and 4-mg/mL suspensions retained >97% of their initial omeprazole concentrations. Suspension viscosities varied 10-fold over the concentrations studied, but all were within the viscosity ranges of other commercially available oral suspensions. Prolonged refrigeration did not increase the suspensions' viscosities. CONCLUSION: Omeprazole-sodium bicarbonate suspensions of 0.6-4 mg/mL omeprazole were stored at 4 degrees C in darkness for up to 28 days. The viscosities of refrigerated suspensions did not increase over 7 days. Except for the 0.6 mg/mL preparations, suspensions stored at room temperature in the light retained >90% of their initial omeprazole content after 7 days, despite turning yellow.

Degradation of lansoprazole and omeprazole in the aquatic environment.

Lansoprazole and omeprazole degrade in water leading to sulfides, benzimidazolones and a red complex material. Degradation is accelerated in acid medium and by solar simulator irradiation. Benzimidazoles, dianilines and pyridines have also been identified.