Stomach problems are often manifested as upper abdominal pain, bloating, tickling cough, belching and heartburn. Most of this happens due to the imbalance between the protective layer of the stomach lining and stomach acids, a result of various factors, such as smoking, a poor diet, stress and drinking too much coffee. However, a balance should be restored. This can be achieved with drugs that either reduce gastric acid secretion or enhance the protective layer of the mucous membrane, which is directly connected to the acid in the stomach. The common choice is omeprazole, a drug belonging to a group of proton pump inhibitors that inhibit gastric acid secretion. It is mainly used to prevent ulcers in the stomach and duodenum associated with the use of NSAIDs (non-steroidal anti-inflammatory drugs), and in combination with appropriate antibiotics to treat ulcers of the stomach and duodenum caused by the bacteria H. pylori.

The mechanism of omeprazole activity

Omeprazole is a therapeutic substance of a weak base and it performs as a pro-drug. The drug concentrates within the parietal cells in the highly acidic environment of the intracellular channels where it is being converted to the active form, which affects the final stage of gastric acid formation. More specifically, it irreversibly impairs the functioning of the ATPase acid pump, inhibiting their secretion in the stomach lumen. However, omeprazole is not an effective medication for all people. In some people the CYP2C19 enzyme is highly active, leading to a premature inactivation of omeprazole, which in result does not fulfil its duties. The final omeprazole inactivation is done in the liver via the CYP2C19 enzyme and it depends on the possible presence of mutations in the CYP2C19 gene. Various studies have shown that almost two-thirds of the Caucasian population has an increased activity of the CYP2C19 enzyme, which is responsible for the fast inactivation of omeprazole. This is then reflected in the reduced effect of the drug and in insufficient inhibition of gastric acid secretion.

While taking omeprazole, attention must be paid to its possible combined use with clopidogrel. Omeprazole “occupies” the CYP2C19 enzyme, which makes it unavailable to convert clopidogrel into an active form. In this case, clopidogrel can be expected to be less effective in preventing blood clotting.