5-alpha-reductase inhibitor 1284673 187583327 2008-01-28T23:55:27Z 201.37.83.168 '''5α-reductase inhibitors''' (or '''5-alpha-reductase inhibitors''') are a group of [[medication|drugs]] with [[antiandrogen]]ic activity, used in the treatment of [[benign prostatic hyperplasia]] and androgenic (or androgenetic) [[alopecia]]. These drugs decrease the levels of available [[5-alpha reductase|5α-reductase]] prior to testosterone binding with the enzyme, thus reducing levels of [[dihydrotestosterone]] that derives from such a bond. ==Clinical use== ===Indications=== 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 reaction]]s (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 [[allergy|allergic]] reaction. (Rossi, 2004) ==Pharmacology== 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. ==Examples== *[[finasteride]] (Proscar, Propecia) *[[dutasteride]] (Avodart) *[[FCE 28260]], an experimental compound ==References== * Rossi S (Ed.) (2004). ''[[Australian Medicines Handbook]] 2004''. Adelaide: Australian Medicines Handbook. ISBN 0-9578521-4-2 {{Urologicals}} [[Category:5-alpha-reductase inhibitors|*]] [[pt:Inibidor da 5-alfa-redutase]]