A patient presents with zo11inger-Ellison syndrome due to gastrinoma. He has two bleeding ulcers and diarrhoea. A drug that irreversibly inhibits the H+/K+ ATPase in gastric parietal cells is:
**Core Concept**
The underlying principle being tested is the management of **Zollinger-Ellison syndrome**, a condition characterized by excessive gastric acid secretion due to a **gastrinoma**, a neuroendocrine tumor that secretes **gastrin**. This leads to severe **peptic ulcer disease** and **diarrhea**. The **proton pump inhibitors (PPIs)** are a class of drugs that inhibit the **H+/K+ ATPase** in gastric parietal cells.
**Why the Correct Answer is Right**
The correct answer is a **proton pump inhibitor (PPI)**, which works by irreversibly inhibiting the **H+/K+ ATPase** in gastric parietal cells, effectively reducing gastric acid secretion. This is crucial in managing **Zollinger-Ellison syndrome**, where excessive acid production leads to severe ulcers and diarrhea.
**Why Each Wrong Option is Incorrect**
**Option A:** Is not specified, but typically, other classes of drugs like **H2 receptor antagonists** would be incorrect as they reversibly inhibit acid secretion.
**Option B:** and **Option C:** are not provided, but any option that does not involve irreversible inhibition of the **H+/K+ ATPase** would be incorrect.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that **PPIs** are most effective when taken before meals, as they need to be activated in the acidic environment of the stomach to irreversibly inhibit the **H+/K+ ATPase**. This is crucial for managing conditions with excessive acid production like **Zollinger-Ellison syndrome**.
**Correct Answer:** D. Proton pump inhibitors, such as omeprazole.