Marked suppression of dihydrotestosterone in men with benign prostatic hyperplasia by dutasteride, a dual 5alpha-reductase inhibitor.
Level 2 - randomized trial
Individual randomized controlled trial comparing multiple doses of dutasteride with finasteride and placebo.
PubMed 15126539 · doi:10.1210/jc.2003-030330
What was done
A total of 399 men with benign prostatic hyperplasia (BPH) were randomized to 24 weeks of once-daily treatment with dutasteride (0.01, 0.05, 0.5, 2.5, or 5.0 mg), finasteride (5 mg), or placebo to compare suppression of serum dihydrotestosterone (DHT).
What was found
Mean serum DHT decreased by 98.4 ± 1.2% with 5.0 mg dutasteride and 94.7 ± 3.3% with 0.5 mg dutasteride, compared with 70.8 ± 18.3% with 5 mg finasteride (P < 0.001). Dutasteride showed greater suppression and less variability. Serum testosterone increased but remained within the normal range across all treatment groups, and dutasteride was well tolerated with an adverse event profile similar to placebo.
Why it matters
Dual inhibition of type 1 and type 2 5alpha-reductase by dutasteride achieves near-complete serum DHT suppression, significantly outperforming the selective type 2 inhibition of finasteride.
Limits
The abstract focuses on hormonal endpoints and does not report clinical efficacy outcomes, such as changes in prostate volume, urinary flow rates, or symptom scores. Specific numerical results for the lower dutasteride doses (0.01 and 0.05 mg) and detailed adverse event rates 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.
- supports Dutasteride administration results in near-complete inhibition of systemic DHT levels.