Pharmacology:Pharmacodynamics: Mechanism of Action: Omeprazole belongs to a new class of anti-secretory compounds, the substituted benzimidazoles, that suppress gastric acid secretion by specific inhibition of the H+/K+ ATPase enzyme system at the secretory surface of the gastric parietal cell. Because this enzyme system is regarded as the acid [proton] pump within the gastric mucosa, omeprazole has been characterized as a gastric acid pump inhibitor, in that it blocks the final step of acid production.