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Question:
A 74-year-old man with urinary frequency and urgency has benign prostatic hyperplasia. He refuses operative intervention but agrees to a trial of finasteride therapy. During the trial, synthesis of which of the following substances is most likely to be inhibited?
Correct Answer: B. Dihydrotestosterone
Finasteride inhibits 5-alpha-reductase, interfering with the conversion of testosterone to dihydrotestosterone (DHT) (choice B). DHT is the primary mediator in the pathogenesis of benign prostatic hyperplasia, causing hyperplasia of glandular and stromal cells.
Androstenedione (choice A) is the precursor to both male and female sex hormones. It can be formed from either dehydroepiandrosterone converted by 3-beta-hydroxysteriod dehydrogenase or 17-alpha-hydroxyprogesterone converted by 17,20 lyase.
Estradiol (choice C) is the major estrogen in humans. Estradiol can be formed by the aromatization of testosterone. Additionally, androstenedione can be aromatized to estrone (choice D) and then converted to estradiol by 17-beta-hydroxysteriod reductase.
Testosterone (choice E) is formed by converting androstenedione via oxidoreductase.
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1. Question
Category: PharmacologyA 74-year-old man with urinary frequency and urgency has benign prostatic hyperplasia. He refuses operative intervention but agrees to a trial of finasteride therapy. During the trial, synthesis of which of the following substances is most likely to be inhibited?
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