Omeprazole
Omeprazole is a proton-pump inhibitor medication (PPI), a so-called “prodrug.” It is converted into its active form as a sulfenamide derivative first in the acidic environment of the gastric mucosa. Omeprazole inhibits the proton-pump: At acidic pH values, the active ingredient accumulates in the parietal cells of the gastric mucosa where it inhibits the H+/K+/ATP – the proton pump's energy source. This blocks the basic acid secretion in the stomach. At the same time, omeprazole has no effect on the H+/K+/ATP of other cells as their pH is too high for it to accumulate.