The presence of moisture in solid dosage forms affects numerous chemical, physical and microbiological properties. This can affect their effectiveness, safety, and quality. Omeprazole is a proton pump inhibitor, which effectively inhibits secretion of stomach acid and has a long-lasting effect. Omeprazole molecule is physically and chemically unstable, therefore it is sensitive to numerous factors such as moisture, elevated temperature, acidic environment, UV light, salts and metal ions. In the Master’s thesis, the effect of moisture and temperature on the chemical stability of omeprazole delayed-release capsules was evaluated. The possibility to predict stability with the help of information, obtained at elevated temperature and/or relative humidity was tested. In addition, the effect of water content and the time of exposure to the test conditions (temperature and relative humidity) on the increase of degradation products was studied. Water content, water activity and the sum of degradation products were determined as main stability parameters. Water content was determined with the Karl Fischer titration, for which a suitable method was first developed and then validated. Furthermore, the practical moisture sorption isotherm, which describes the relationship between water activity and equilibrated amount of absorbed water, was determined. For this purpose, a method for the determination of water activity was developed and validated. From known compositions of pellets and obtained sorption isotherms for active pharmaceutical ingredient and excipients, a theoretical sorption isotherm was calculated and compared with the practical sorption isotherm. Minor deviations between two isotherms were result of dosage forms complexity. Elevated levels of moisture in dosage form affected the increase of degradation products. Comparison of differently dried capsules before packaging revealed that dosage forms with a low starting water content were more stable. In the research was shown that the hygroscopicity of the active pharmaceutical ingredient affects its chemical stability in delayed-release pellets, packed in hard gelatin capsules. The prediction of stability was performed with a calculation, based on humidity-corrected Arrhenius equation, moisture vapor transmission rate (MVTR) and sorption-desorption moisture transfer (SDMT) between components in packaging.
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