Finasteride: an update of its use in the management of symptomatic benign prostatic hyperplasia

Finasteride inhibits type 25alpha-reductase activity, significantly reducing dihydrotestosterone levels. Consequent reductions in prostate volume, increases in urinary flow rates and improvements in symptoms compared with placebo have been observed in trials of up to 4 years' duration and in noncomparative extensions (for up to 6 years). Results from the 4-year placebo-controlled PLESS trial show finasteride to significantly reduce the risk of benign prostatic hypertrophy (BPH)-related acute urinary retention and the requirement for surgical intervention. Finasteride has significantly greater efficacy in patients with a large prostate (> or = 40 ml) than in patients with a small prostate. However, the predictive value of prostate size has been questioned. Results of an earlier comparative 1-year trial show terazosin monotherapy and terazosin plus finasteride therapy to be significantly more effective than both finasteride monotherapy and placebo in reducing symptom scores and improving maximum urinary flow rates. Prostatic volume was significantly reduced by finasteride monotherapy and combination therapy only. The overall efficacy of finasteride in patients with mild to moderate symptomatic BPH tended to be greater than that of serenoa repens (Permixon) in a 6-month trial. A US cost analysis model indicates that finasteride and terazosin are less expensive than transurethral resection of the prostate (TURP) during the first 2 years of initiation. Canadian cost-effectiveness and cost-utility analyses using decision analysis modelling have shown primary intervention with finasteride to provide more quality-adjusted life years (QALYs) at lesser cost than watchful waiting or TURP in patients with moderate symptoms who receive the drug for < or = 3 years and < or = 14 years, respectively, but fewer QALYs at a higher cost in patients with severe symptoms needing therapy for > or = 4 years. Confirmatory prospective economic studies are required. Finasteride appears to improve overall quality of life to a similar extent to serenoa repens; patient satisfaction appears similar with finasteride and TURP. Finasteride is generally well tolerated. Most commonly reported adverse effects are sexually related (1 to 2.1 %). Gynaecomastia has been reported in 0.4% of patients.

Despite modest improvements in maximum urinary flow rates and symptom scores, finasteride is a first-line treatment option in those with moderate uncomplicated BPH, especially in patients with a large prostate (> or = 40 ml). It is also an option in patients with more severe symptoms who are unable or unwilling to undergo surgery and in those awaiting surgery. Importantly, finasteride appears to reduce disease progression, significantly decreasing the incidence of acute urinary retention and the requirement for surgical intervention; to date, no other pharmacological agent has been shown to reduce these outcomes.