Drug not causing gynaecomastia is?
**Core Concept**
Gynaecomastia is a clinical condition characterized by the enlargement of breast tissue in males, often resulting from an imbalance between estrogen and androgen hormones. This condition can be caused by various medications that affect hormone levels or signaling pathways.
**Why the Correct Answer is Right**
The correct answer is **A. Metoprolol**. Metoprolol, a beta-blocker, does not directly affect hormone levels or signaling pathways, making it an unlikely cause of gynaecomastia. Unlike other medications, metoprolol does not have significant anti-androgen or estrogenic properties, which are often associated with gynaecomastia.
**Why Each Wrong Option is Incorrect**
* **Option B: Spironolactone** is a potassium-sparing diuretic that also has anti-androgen effects, which can lead to gynaecomastia by blocking androgen receptors.
* **Option C: Digoxin** can cause gynaecomastia by increasing estrogen levels, possibly due to its effect on the hypothalamic-pituitary-gonadal axis.
* **Option D: Cimetidine** is a histamine H2-receptor antagonist that can cause gynaecomastia by inhibiting the metabolism of estrogen, leading to an increase in estrogen levels.
**Clinical Pearl / High-Yield Fact**
When evaluating patients for gynaecomastia, consider medications with anti-androgen or estrogenic properties, such as spironolactone, cimetidine, and digoxin, which can contribute to hormonal imbalances.
**Correct Answer:** A. Metoprolol