Benign Prostatic Hyperplasia
Finasteride is used to reduce prostatic size, urinary obstruction and associated manifestations (e.g., urinary hesitancy and/or urgency, nocturia), the risk of acute urinary retention, and the risk of the need for surgery (including transurethral resection of the prostate [TURP] and prostatectomy) in patients with symptomatic benign prostatic hyperplasia (BPH, benign prostatic hypertrophy). Finasteride also is used concomitantly with an α1-adrenergic blocking agent (e.g., doxazosin) to decrease the risk of symptomatic progression of BPH.
BPH, an abnormal enlargement of the prostate gland that occurs in most men 55 years of age or older, produces manifestations such as a weak urinary stream, difficulty in initiating urination, and urinary frequency and urgency. Urinary flow obstruction secondary to BPH historically has been treated with surgical correction of the hyperplasia (e.g.,via TURP). However, medical therapy with a 5α-reductase inhibitor (e.g., finasteride, dutasteride) and/or other drugs (e.g., α1-adrenergic blocking agents such as alfuzosin, doxazosin, tamsulosin, or terazosin) may be a useful alternative to surgery in patients who are awaiting or are unwilling to undergo surgical correction of the hyperplasia or who are at increased risk from or are not candidates for such surgery. Although drug therapy usually is not as effective as surgical therapy, it may provide adequate symptomatic relief with fewer and less serious adverse effects compared with surgery.
Therapy with either a 5α-reductase inhibitor (e.g., finasteride) or an α1-adrenergic blocker is effective in partially relieving lower urinary tract symptoms, although therapy with an α1-adrenergic blocker appears to result in greater symptomatic improvement. Finasteride also has been shown to decrease the risk of acute urinary retention and the need for BPH-related surgery.
Most experts currently consider therapy with a 5α-reductase inhibitor to be an appropriate option for treatment of bothersome lower urinary tract symptoms in patients with BPH who have evidence of prostatic enlargement. Therapy with a 5α-reductase inhibitor is ineffective in patients who do not have evidence of prostatic enlargement. Most experts state that therapy with a 5α-reductase inhibitor also may be considered in patients who have symptomatic prostatic enlargement but whose symptoms are not bothersome (i.e., do not interfere with activities of daily living) in order to prevent progression of the disease. However, the disadvantages of this therapeutic approach (e.g., adverse effects including sexual dysfunction, the need for long-term daily therapy) should be discussed with the patient relative to that individual's risk for acute urinary retention and potential risks associated with BPH-related surgery so that an informed decision can be made.
Results of a long-term (4-year) controlled clinical study in patients with moderate to severe symptoms of BPH indicate that finasteride (5 mg daily) reduces symptoms of BPH, reduces prostatic size and increases urinary flow rate, and reduces the risk of acute urinary retention and the need for surgery. In this study, treatment with finasteride or placebo for 4 years reduced symptom scores by a mean of 3.3 or 1.3 points, respectively, from an average baseline score of 15 (as measured on a scale of 0-34, with the total score equal to the sum of the scores for 7 measures of obstructive or irritative symptoms). A difference in symptom scores between treatment groups was evident within the first year of treatment and continued throughout the 4-year study. In general, at least 6 months of therapy was required to determine whether a beneficial reduction in symptoms had been achieved, although some patients experienced earlier improvement. Prostatic volume decreased during the first year of the study in patients receiving finasteride and then remained stable during years 2-4, whereas values in the placebo group increased steadily over the 4 years of the study. Acute urinary retention requiring catheterization of the bladder occurred in 2.8 or 6.6% of patients receiving finasteride or placebo, respectively, and 4.6 or 10.1% of patients receiving finasteride or placebo, respectively, underwent surgery for BPH.
Results of a meta-analysis of 1 year of data from 7 similarly designed controlled studies indicate that improvements in symptoms and maximum urinary flow rates associated with finasteride therapy are greater in patients with prostatic enlargement at baseline.
Finasteride therapy in BPH appears to be suppressive rather than curative, and eventual return of the hyperplasia likely will occur if the drug is withdrawn.
Finasteride may be used concomitantly with an α1-adrenergic blocking agent (e.g., doxazosin, alfuzosin, terazosin) to decrease the risk of symptomatic progression of BPH (i.e., an increase from baseline of at least 4 on the American Urological Association [AUA] symptom score). Although studies of up to 1 year in duration generally have found combination therapy with a 5α-reductase inhibitor (e.g., finasteride) and an α1-adrenergic blocker to be no more effective than α1-adrenergic blocker monotherapy in providing symptomatic relief of BPH, a long-term (mean follow-up: 4.5 years), double-blind study (Medical Therapy of Prostatic Symptoms [MTOPS]) found that combined therapy with finasteride (5 mg daily) and doxazosin (4-8 mg daily) was more effective than therapy with either drug alone in preventing symptom progression (defined as an increase from baseline of at least 4 points in the AUA symptom score, acute urinary retention, urinary incontinence, renal insufficiency, or recurrent urinary tract infection). The percent reduction in the risk of symptom progression (generally manifested as an increase in AUA symptom score) relative to placebo was 34% with finasteride, 39% with doxazosin, and 67% with combination therapy. The risks of long-term acute urinary retention and the need for invasive therapy were reduced by combination therapy and by finasteride monotherapy but not by doxazosin monotherapy. Combination therapy or doxazosin or finasteride monotherapy each were effective in providing improvement in symptom scores, with combination therapy providing greater improvement than either drug alone.
Most experts state that combined therapy with a 5α-reductase inhibitor and an α1-adrenergic blocker can be considered for men with bothersome moderate to severe BPH and demonstrable prostatic enlargement, weighing the benefit of preventing progression of BPH with the risks and cost of the combination. Men at risk for BPH progression are most likely to benefit from combination therapy. Although the benefit of combination therapy was not as substantial in men with low baseline prostate-specific antigen (PSA) levels compared with those with high baseline values in the MTOPS study, the potential benefit appears to be greatest in those in whom baseline risk of progression generally is high rather than specifically in those with larger prostates or higher PSA levels at baseline.
Adverse effects associated with combined 5α-reductase inhibitor and α1-adrenergic blocker therapy generally reflect the combined toxicity profile of each drug alone, although certain adverse effects (e.g., effects on sexual function and libido, postural hypotension, peripheral edema, dizziness, asthenia, rhinitis) may be more common with combined therapy.
For further information on the treatment of BPH, .
For use in the management of alopecia,