Which among the following is not an androgen receptor blocker?
**Core Concept**
Androgen receptor blockers are a class of medications that inhibit the action of androgens (male hormones) by blocking their binding to the androgen receptor. This is used in the treatment of conditions such as benign prostatic hyperplasia (BPH), acne, and androgenetic alopecia.
**Why the Correct Answer is Right**
The correct answer is not an androgen receptor blocker because it does not inhibit the binding of androgens to the androgen receptor. Androgen receptor blockers work by competing with androgens for binding sites on the androgen receptor, thereby reducing the androgenic effects. This is in contrast to the correct answer, which may work through a different mechanism.
**Why Each Wrong Option is Incorrect**
**Option A:** **Finasteride** is an androgen receptor blocker, specifically a 5-alpha-reductase inhibitor that blocks the conversion of testosterone to dihydrotestosterone (DHT), a potent androgen.
**Option B:** **Dutasteride** is also an androgen receptor blocker, a 5-alpha-reductase inhibitor that blocks the conversion of testosterone to DHT.
**Option C:** **Spironolactone** is not an androgen receptor blocker, but rather a potassium-sparing diuretic and an aldosterone antagonist.
**Clinical Pearl / High-Yield Fact**
Androgen receptor blockers can cause gynecomastia (breast enlargement in men) due to the unopposed estrogenic effects of testosterone and DHT.
**Correct Answer:** C. Spironolactone is not an androgen receptor blocker.