Pepsin A3 Inhibitors

Pepsin A3 Inhibitors are a group of compounds that directly or indirectly lead to the decreased functional activity of Pepsin A3, a protease that requires an acidic environment to be fully active. One of the direct inhibitors, Pepstatin A, binds to the active site of Pepsin A3, preventing it from interacting with its substrates and thus inhibiting its proteolytic activity. This direct inhibition is a specific interaction that ensures the substantial reduction of Pepsin A3's function. On the other hand, several indirect inhibitors function by altering the pH of the stomach. Proton pump inhibitors such as Omeprazole, Lansoprazole, Esomeprazole, Pantoprazole, and Rabeprazole work by suppressing the secretion of gastric acid via specific inhibition of the H+/K+ ATPase in the gastric parietal cells. By doing so, these inhibitors raise the pH of the stomach, creating a less acidic and thus less optimal environment for Pepsin A3, which in turn hampers its activity.

Furthermore, H2 histamine receptor antagonists like Ranitidine and Famotidine decrease gastric acid production by blocking the action of histamine on the H2 receptors of parietal cells, again resulting in an increased gastric pH and subsequent indirect inhibition of Pepsin A3. Antacids, including Calcium carbonate, Magnesium hydroxide, and Aluminum hydroxide, neutralize stomach acid, which leads to a temporary increase in gastric pH. While these do not stop the acid production, they buffer the acidity, making it unfavorable for Pepsin A3 to function effectively.