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5-alpha-reductase inhibitor

5α-reductase inhibitors (or 5-alpha-reductase inhibitors) are a group of drugs with antiandrogenic activity, used in the treatment of benign prostatic hyperplasia and androgenic (or androgenetic) alopecia. These drugs decrease the levels of available 5α-reductase prior to testosterone binding with the enzyme, thus reducing levels of dihydrotestosterone that derives from such a bond.


Clinical use


5α-reductase inhibitors are clinically used in the treatment of conditions which are exacerbated by dihydrotestosterone. Specifically, these indications may include: (Rossi, 2004)

  • mild-to-moderate benign prostatic hyperplasia
  • androgenic (or androgenetic) alopecia

Adverse drug reactions

Adverse drug reactions (ADRs) experienced with 5α-reductase inhibitors are generally dose-dependent. Common ADRs include impotence, decreased libido, decreased ejaculate volume. Rare ADRs include: breast tenderness and enlargement, and allergic reaction. (Rossi, 2004)


The enzyme 5α-reductase is involved in the conversion of testosterone to the active form dihydrotestosterone by reducing the Δ4,5 double-bond. In benign prostatic hyperplasia, dihydrotestosterone acts as a potent cellular androgen and promotes prostate growth - inhibiting the enzyme reduces the excessive prostate growth. In alopecia, pattern-baldness is one of the effects of androgenic receptor activation. Reducing the levels of dihydrotestosterone thus reduces alopecia.



This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "5-alpha-reductase_inhibitor". A list of authors is available in Wikipedia.
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