Omeprazole half life
Pro Research Analysisby 
Searched over 200M research papers
Omeprazole Half-Life: An Overview
Introduction to Omeprazole
Omeprazole is a widely used proton pump inhibitor (PPI) that effectively reduces gastric acid secretion by inhibiting the H+/K+ ATPase enzyme in the stomach's parietal cells. It is commonly prescribed for conditions such as gastroesophageal reflux disease (GERD), peptic ulcers, and Zollinger-Ellison syndrome.
Pharmacokinetics and Metabolism
Absorption and Distribution
Omeprazole is acid-labile, meaning it degrades quickly in acidic environments. Therefore, it is administered as enteric-coated granules to protect it from stomach acid. Once ingested, omeprazole is rapidly absorbed, with peak plasma concentrations occurring within 0.5 to 3 hours depending on the formulation 37. The drug is highly protein-bound and has a volume of distribution corresponding to the volume of extracellular water .
Elimination Half-Life
The elimination half-life of omeprazole is relatively short, typically less than 1 hour in healthy individuals 37. Despite this short plasma half-life, the drug's pharmacological effects last much longer due to its irreversible binding to the H+/K+ ATPase enzyme in parietal cells . This binding results in prolonged inhibition of acid secretion, lasting up to 24 hours or more.
Factors Affecting Half-Life
Age
In elderly individuals, the metabolic capacity for omeprazole is reduced, leading to a longer elimination half-life of approximately 1 hour compared to 0.7 hours in younger individuals . This is due to decreased systemic clearance and increased bioavailability in the elderly.
Drug Interactions
Omeprazole can interact with other drugs metabolized by the liver's cytochrome P450 system, particularly CYP2C19 and CYP3A4. For instance, it has been shown to prolong the half-life of diazepam and phenytoin by inhibiting their hepatic metabolism 67. These interactions can lead to increased plasma levels and prolonged effects of the co-administered drugs.
Stability and Formulation
Stability in Different Formulations
The stability of omeprazole varies significantly depending on its formulation and the presence of stabilizers. For example, enteric-coated microcapsules containing arginine have a half-life of 194 days, while compression-coated tablets with lysine have a half-life of 292 days . These formulations help protect omeprazole from degradation in the acidic environment of the stomach, ensuring its efficacy.
Racemisation Half-Life
The racemisation half-life of omeprazole, which refers to the time it takes for the drug to convert between its enantiomeric forms, is estimated to be around 130 hours at 37°C . This aspect is crucial for understanding the drug's stability and efficacy over time.
Conclusion
Omeprazole is a potent and effective PPI with a short plasma half-life but prolonged pharmacological effects due to its irreversible binding to the H+/K+ ATPase enzyme. Its stability and half-life can be influenced by factors such as age, drug interactions, and formulation. Understanding these factors is essential for optimizing its therapeutic use and managing potential interactions with other medications.
Sources and full results
Most relevant research papers on this topic