Proton pump inhibitors (PPIs) are a group of drugs whose main action is a pronounced and long-lasting reduction of gastric acid production. Within the class of medications — esomeprazole, lansoprazole, omeprazole, pantoprazole, and rabeprazole — there is no clear evidence that one agent works better than another.
They are the most potent inhibitors of acid secretion available. This group of drugs followed and largely superseded another group of medications with similar effects, but a different mode of action, called H2-receptor antagonists.

Proton pump inhibitors act by irreversibly blocking the hydrogen/potassium adenosine triphosphatase enzyme system (the H+/K+ ATPase or, more commonly, the gastric proton pump) of the gastric parietal cells. The proton pump is the terminal stage in gastric acid secretion, being directly responsible for secreting H+ ions into the gastric lumen, making it an ideal target for inhibiting acid secretion.
Targeting the terminal step in acid production, as well as the irreversible nature of the inhibition, results in a class of drugs that are significantly more effective than H2 antagonists and reduce gastric acid secretion by up to 99%.

These drugs are used in the treatment of:
- dyspepsia
- peptic ulcer disease
- as part of Helicobacter pylori eradication therapy
- gastroesophagal reflux disease
- Barrett's esophagus
- eosinophilic esophagitis
- stress gastritis and ulcer prevention
- gastrinomas

Adapted from Wikipedia, the free encyclopedia. Internet. Accessed on March 13, 2017.