The clinical applications of five-alpha reductase inhibitors.
Level 5 - mechanism / opinion, no new human data
Narrative literature review without systematic review methodology or meta-analysis
What was done
A Medline search was conducted using MeSH terms for benign prostatic hypertrophy, prostate cancer, male pattern baldness, female, and 5-alpha reductase (5-AR). The authors reviewed pharmacological data and major clinical trial findings for the 5-AR inhibitors finasteride (type 2 isoenzyme inhibitor) and dutasteride (dual type 1 and 2 isoenzyme inhibitor).
What was found
In the PLESS trial, finasteride resulted in a 22% increase in maximum flow rate, a 19% decrease in prostate volume, and a significant reduction in the 4-year risk of prostate surgery and urinary retention; dutasteride showed similar benefits. In the 7-year PCPT chemoprevention trial, 18.4% of the finasteride group developed prostate cancer compared to 24.4% in the placebo group. In the 4-year REDUCE trial, dutasteride achieved a 22.8% reduction in prostate cancer. Both prevention trials noted an increased risk of high-grade prostate cancer in treatment arms. Low-dose finasteride was also effective for male pattern baldness.
Why it matters
This review outlines the clinical indications and primary trial evidence for 5-alpha reductase inhibitors across benign prostatic hyperplasia, prostate cancer chemoprevention, and male pattern hair loss.
Limits
The paper is a narrative review without formal systematic inclusion criteria, risk-of-bias evaluation, or pooled statistical analyses. Total patient and study numbers are not specified in the abstract, and findings regarding female applications mentioned in the search strategy are omitted.
Cited by
- contradicts Finasteride inhibits two of the three 5-alpha reductase isoenzymes, resulting in approximately 60 to 70% inhibition of systemic DHT.