Finasteride and dutasteride appear to have similar efficacy in benign prostatic hyperplasia (BPH) over 12 months, a head-to-head study has shown.

A total of 1,630 men with BPH were randomised to receive either dutasteride 0.5 mg (n=813) or finasteride 5 mg (n=817) daily in the EPICS study. The international trial was a prospective year-long double blind, parallel group study. Inclusion criteria were age >50 years, AUA Symptom Index (AUA-SI score) >12, prostate volume >30 cm3 on ultrasound and flow rate

Both finasteride and dutasteride reduced prostate volume during the study, the former by 26.7% and the latter by 26.3%, at 12 months. Symptom scores also fell, by 5.5 points for finasteride and 5.8 points for dutasteride. PSA values decreased, as expected, with a 47.7% reduction from baseline for finasteride and 49.5% for dutasteride.

Similar adverse event rates were seen with the two drugs, most commonly erectile dysfunction (9% of patients on finasteride and 8% on dutasteride) and decreased libido (6% and 5% respectively).

What can we conclude from this study? First, the patient group under study is consistent with the patient population recommended for 5-ARI treatment by NICE, and both finasteride and dutasteride perform well in terms of prostate volume reduction and symptom control.

(A placebo arm would be expected to have shown a small increase in prostate volume and a deterioration in symptom scores during the 12 months of the study, thus increasing the treatment effect with 5-ARIs.)

PSA results roughly halved as would be expected and this reinforces the message that GPs must double PSA results for comparison with age-specific ranges in men who have been treated with 5-ARIs for >6 months.

No clinical advantage was seen in the study for dutasteride versus finasteride. Both dutasteride and finasteride inhibit type 2 5-alpha reductase, the dominant enzyme in benign prostatic tissue. Dutasteride also inhibits type 1 5-alpha reductase, so-called dual inhibition, and this provides significantly greater suppression of serum dihydrotestosterone than finasteride.

Finasteride is now off patent and the generic version is therefore considerably cheaper to prescribe than dutasteride.

Studies such as COMBAT have shown the prolonged benefit of 5-ARIs at least up to five years, and thus the major limitation of this study is its relatively short duration of 12 months. 5-ARIs should be considered to be long-term therapy, and thus longer follow-up of these two arms would be of even greater interest.

Long-term studies of combination therapy with finasteride and tamsulosin versus dutasteride and tamsulosin would also be of great clinical interest.

Dr Jonathan Rees