Which of the following compound is not an actacid?

Options

A. Aluminium hydroxide
B. Cimetidine
C. Phenelzine
D. RAnitidine

Explanation

To determine which of the following compounds is not an antacid, we first need to understand what an antacid is. An antacid is a substance that neutralizes stomach acidity, typically acting as a weak base.

1. **Identify the Compounds**:
- Option A: Aluminium hydroxide
- Option B: Cimetidine
- Option C: Ranitidine
- Option D: Phenelzine

2. **Evaluate Each Compound**:
- **Aluminium Hydroxide**: This is a mild base and is commonly used as an antacid to reduce stomach acidity.
- **Cimetidine**: This is a histamine H2-receptor antagonist that also acts as a weak base, helping to reduce stomach acidity. It is used to treat conditions like ulcers and gastroesophageal reflux disease (GERD).
- **Ranitidine**: Similar to cimetidine, ranitidine is also a histamine H2-receptor antagonist that reduces stomach acid production and is used as an antacid.
- **Phenelzine**: This compound is not a base; it is a selective and irreversible monoamine oxidase inhibitor (MAOI) used primarily as an antidepressant.

3. **Conclusion**:
- From the evaluation, we see that Aluminium hydroxide, Cimetidine, and Ranitidine are all antacids as they can neutralize stomach acidity. However, Phenelzine does not serve this purpose and is not an antacid.

Thus, the compound that is not an antacid is **Phenelzine**.