What is the role of 5-alpha-reductase inhibitors (5-ARIs) in the treatment of benign prostatic hyperplasia (BPH)?

Updated: Feb 19, 2021
  • Author: Levi A Deters, MD; Chief Editor: Edward David Kim, MD, FACS  more...
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Two 5-alpha-reductase inhibitors (5-ARIs) are approved for use in BPH: finasteride (Proscar) and dutasteride (Avodart). American Urological Association (AUA) guidelines advise that in men with lower urinary tract symptoms (LUTS) and enlarged prostates, 5-ARIs may help prevent progression of LUTS secondary to BPH and reduce the risk of urinary retention and future prostate-related surgery. The AUA notes that prostatic enlargement can be determined by volume measurement, prostate-specific antigen (PSA) l level as a proxy for volume, and/or digital rectal examination. [1]

Unlike alpha-blockers, which work by reducing smooth muscle tone, 5-ARIs improve LUTS by reducing prostate volume. Thus, patients with larger prostates may achieve a greater benefit. Maximal reduction in prostate volume requires 6 months of therapy.

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