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Efficacy and safety of dutasteride

Created: 1/10/2006
Updated: 27/2/2007


Efficacy and safety of a dual inhibitor of 5-alpha-reductase types 1 and 2 (dutasteride) in men with benign prostatic hyperplasia
Roehrborn CG, Boyle P, Nickel JC, Hoefner K, Andriole G;
Urology. 2002 Sep;60(3):434-41


  • Di-hydrotestosterone (DHT) is the primary androgen responsible for prostatic enlargement and BOO
  • The disease is progressive with risk factors for progression including age, PSA and prostatic size
  • Two classes of medication exist for BPH; alpha-blockers and 5-alpha-reductase inhibitors
  • Finasteride is a selective inhibitor of the type-II 5-alpha-reductase isoenzyme
  • Finasteride reduces prostate volume by approx 20%, improves symptoms, reduces bother and was show in the PLESS trial to reduce the risk of surgery/AUR by 50% compared with placebo
  • Finasteride, via the inhibition of 5-alpha-reductase, reduces circulating testosterone levels by approx 70%
  • The remainder is probably produced via the action of type-I 5-alpha-reductase
  • Dutasteride inhibits both type I and II 5-alpha-reductase and as a result can reduce serum DHT by more than 90%
  • The current study investigates the efficacy and safety of dutasteride


  • 4325 men (2951 completed) were included with:
    • clinical benign prostatic hyperplasia
    • moderate to severe symptoms (American Urological Association-Symptom Index score of 12 points or greater)
    • peak flow rate of 15 mL/s or less
    • prostate volume of 30 cm3 or greater (as measured by transrectal ultrasonography)
    • serum prostate-specific antigen level of 1.5 to 10.0 ng/mL (inclusive)
  • Patients were enrolled into three identical clinical trials and randomized to 0.5 mg dutasteride daily or placebo
  • After a 1-month, single-blind, placebo lead-in, patients were followed up for 24 months in a double-blind trial with multiple interval assessments


  • At 24 months:
    • Serum dihydrotestosterone was reduced from baseline by a mean of 90.2% (median -93.7%; P <0.001)
    • Testosterone levels stayed within normal ranges for all groups
    • Total prostate and transition zone volumes were reduced by a mean of 25.7% and 20.4%, respectively (P <0.001)
    • The symptom score was improved by as early as 3 months, with pooled significance from 6 months onward (P <0.001) and a reduction of 4.5 points (21.4%) at 24 months (P <0.001)
    • The maximal flow rate improved significantly from 1 month (P <0.01), with an increase of 2.2 mL/s reported at 24 months (P <0.001)
    • The risk reduction of acute urinary retention was 57% and the risk reduction of benign prostatic hyperplasia-related surgical intervention was 48% compared with placebo
  • The drug was well tolerated


  • Only patients with prostate volume of =30cm3 and a PSA of = 1.5ng/ml (patients with increased risk of disease progression)
  • Dutasteride inhibits type I and II isoenzymes
  • Reduction in symptom score with dutasteride is comparable to that achieved with finasteride and many alpha-blockers
  • Qmax was increased by 2.2mls by dutasteride , finasteride achieved improvements of 1.6-1.9ml/s in the PLESS study, Veterans Affairs Study and Predict trial
  • Serum total PSA is reduced by a mean of approx. 50% - to preserve utility it must be multiplied by 2
  • Risk of AUR and surgery in the placebo arm was 4.2% and 4.1% respectively; this was reduced in the dutasteride arm to 1.8% and 2.2%
  • This represents a risk reduction with dutasteride of 57% for AUR and 48% for surgery
  • Similar finasteride vs placebo data for AUR is 1.1% vs 2.7%
  • Discontinuation due to adverse events (AE’s) was rare
  • Sexually related AE’s were more common in the dutasteride group (eg ED 4% placebo, 7.3% dutasteride)
  • AE result equivocal to finasteride, therefore increased DHT suppression does not equate to increased number/severity of AE’s

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