Dutasteride: a novel dual inhibitor of 5alpha-reductase for benign prostatic hyperplasia.

Dutasteride is a new dual 5alpha-reductase inhibitor for the treatment of benign prostatic hyperplasia. It differs from finasteride as it inhibits both isoenzymes of 5alpha-reductase and results in near-complete suppression of serum dihydro-testosterone. Similar to finasteride, it reduces serum prostatic specific antigen by approximately 50% at 6months and total prostate volume by 25% in 2years. Randomised, placebo-controlled trials conducted over 2years 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 the need for surgery. The main side effects are erectile dysfunction, decreased libido, gynaecomastia and ejaculation disorders. However, long-term usage for > 4years did not reveal increased new onset of sexual side effects. In addition, the combination of dutasteride and tamsulosin is well-tolerated and has the added advantage of rapid symptomatic relief. Finally, dutasteride has been shown to possess tumour regression properties invitro and its role in chemoprevention of prostate cancer will be confirmed in the ongoing Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial.