Question

What is the mechanism of action for the drug Omeprazole?

• A. H$_2$ receptor antagonist
• B. Proton pump inhibitor
• C. Anticholinergic agent
• D. Antacid

Hint:

Important Proton Pump Inhibitors (PPIs):

• \textbf{Omeprazole}
• \textbf{Pantoprazole}
• \textbf{Lansoprazole}
• \textbf{Rabeprazole}
• \textbf{Esomeprazole}

Mnemonic: \textbf{“OPLRE”} – Omeprazole, Pantoprazole, Lansoprazole, Rabeprazole, Esomeprazole. \textbf{Mechanism:} Inhibition of the H$^+$/K$^+$–ATPase proton pump in gastric parietal cells.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Omeprazole is a widely used medication for the treatment of gastroesophageal reflux disease (GERD), peptic ulcer disease, and other acid-related disorders.
It reduces gastric acid secretion by targeting the final step of acid production in the stomach.
Step 2: Key Approach:
Identify the molecular target of Omeprazole in the gastric parietal cells.
Step 3: Detailed Explanation:
Omeprazole is a prodrug that gets activated in the acidic environment of the gastric parietal cells.
Once activated, it irreversibly binds to the \(H^+/K^+\) ATPase enzyme system, commonly known as the proton pump.
This inhibition blocks the final common pathway of gastric acid secretion, effectively reducing gastric acidity.
\(H_2\) receptor antagonists (like Ranitidine) block histamine receptors, which is a different mechanism.
Antacids (like Calcium Carbonate) simply neutralize existing stomach acid chemically.
Anticholinergic agents block muscarinic receptors to reduce acid, but are rarely used now due to side effects.
Step 4: Final Answer:
Omeprazole functions as a Proton pump inhibitor.