A 52-year-old man is prescribed dutasteride 500mcg daily for BPH. Which statement best describes its mode of action?

A 52-year-old man is prescribed dutasteride 500mcg daily for BPH. Which statement best describes its mode of action?

• A. Dutasteride inhibits 5-alpha reductase enzymes, reducing the conversion of testosterone to DHT
• B. Inhibits aromatase
• C. Binds beta-adrenergic receptors
• D. Inhibits HMG-CoA reductase

Answer: (A)

Dutasteride works by blocking the enzymes that convert testosterone to dihydrotestosterone (DHT). It inhibits both 5-alpha reductase isoforms, which lowers DHT levels in the prostate and circulation. Since DHT is a more potent androgen in prostatic tissue and drives growth by acting on androgen receptors, reducing DHT decreases prostate size and helps relieve BPH symptoms. The other options describe mechanisms that don’t affect DHT production or prostatic growth—aromatase inhibition alters estrogen synthesis, beta-adrenergic receptor binding affects sympathetic signaling, and HMG-CoA reductase inhibition reduces cholesterol production.

Dutasteride works by blocking the enzymes that convert testosterone to dihydrotestosterone (DHT). It inhibits both 5-alpha reductase isoforms, which lowers DHT levels in the prostate and circulation. Since DHT is a more potent androgen in prostatic tissue and drives growth by acting on androgen receptors, reducing DHT decreases prostate size and helps relieve BPH symptoms. The other options describe mechanisms that don’t affect DHT production or prostatic growth—aromatase inhibition alters estrogen synthesis, beta-adrenergic receptor binding affects sympathetic signaling, and HMG-CoA reductase inhibition reduces cholesterol production.