Dutasteride is used in the treatment of
benign prostatic hyperplasia. Like
finasteride, it reduces serum
prostate-specific antigen levels by approximately 50% at 6 months and total prostate volume by 25% in 2 years. It differs from
finasteride in that it inhibits both
isoenzymes of 5alpha
reductase and results in near-complete suppression of serum
dihydrotestosterone. Randomized placebo-controlled trials over 2 years have shown the efficacy of
dutasteride in symptomatic relief, improvements in quality of life and peak urinary flow rate, and reduction of acute
urinary retention events and need for surgery. Side effects occurring in
therapy with
dutasteride are decreased libido,
erectile dysfunction, ejaculation disorders, and
gynecomastia. However, when
dutasteride treatment is compared with placebo, these sexual adverse events are only modestly elevated. Long-term use over 4 years did not increase side effects. An efficient treatment of side effects is the combination of
dutasteride and
tamsulosin, especially for patients with large prostate volumes. Finally, the anticancer properties of
dutasteride have been shown in placebo-controlled trials and are being investigated in the ongoing Reduction by
Dutasteride of
Prostate Cancer Events (REDUCE) trial.