Finasteride 5 mg/day was initially evaluated in patients with symptoms of BPH and enlarged prostates by digital rectal examination in two 1-year, placebo-controlled, randomized, double-blind studies and their 5-year open extensions.
Finasteride was further evaluated in the finasteride long-term efficacy and safety study, a double-blind, randomized, placebo-controlled, 4-year, multicenter study. 3040 patients between the ages of 45 and 78, with moderate to severe symptoms of BPH and an enlarged prostate upon digital rectal examination, were randomized into the study (1524 to finasteride, 1516 to placebo) and 3016 patients were evaluable for efficacy. 1883 patients completed the 4-year study (1000 in the finasteride group, 883 in the placebo group).
Effect on Symptom Score
Symptoms were quantified using a score similar to the American Urological Association Symptom Score, which evaluated both obstructive symptoms (impairment of size and force of stream, sensation of incomplete bladder emptying, delayed or interrupted urination) and irritative symptoms (nocturia, daytime frequency, need to strain or push the flow of urine) by rating on a 0 to 5 scale for six symptoms and a 0 to 4 scale for one symptom, for a total possible score of 34.
Patients in a long-term efficacy and safety study had moderate to severe symptoms at baseline (mean of approximately 15 points on a 0 to 34 point scale). Patients randomized to finasteride who remained on therapy for 4 years had a mean (± 1 SD) decrease in symptom score of 3.3 (± 5.8) points compared with 1.3 (± 5.6) points in the placebo group. (See Figure 1.) A statistically significant improvement in symptom score was evident at 1 year in patients treated with finasteride vs placebo (–2.3 vs –1.6), and this improvement continued through Year 4.
Figure 1 Symptom Score in a Long-Term Efficacy and Safety Study
Image Of Figure 1 (Finasteride Fig 2)
Results seen in earlier studies were comparable to those seen in a long-term efficacy and safety study. Although an early improvement in urinary symptoms was seen in some patients, a therapeutic trial of at least 6 months was generally necessary to assess whether a beneficial response in symptom relief had been achieved. The improvement in BPH symptoms was seen during the first year and maintained throughout an additional 5 years of open extension studies.
Effect on the Need for Surgery
In a long-term efficacy and safety study, efficacy was also assessed by evaluating treatment failures. Treatment failure was prospectively defined as BPH-related urological events or clinical deterioration, lack of improvement and/or the need for alternative therapy. BPH-related urological events were defined as urological surgical intervention. Complete event information was available for 92% of the patients. The following table (Table 5) summarizes the results.
Table 5:
All Treatment Failures in a Long-Term Efficacy and Safety Study
|
| Patients (%)
patients with multiple events may be counted more than once for each type of event |
|
|
|
| Event | Placebo N=1503
| Finasteride N=1513
| Relative Risk
Hazard ratio based on log rank test | 95% CI | P Value
|
| All Treatment Failures | 37.1 | 26.2 | 0.68 | (0.57 to 0.79) | <0.001 |
Surgical
Interventions for
BPH
| 10.1 | 4.6 | 0.45 | (0.32 to 0.63) | <0.001 |
Two consecutive
symptom scores
≥20
| 9.2 | 6.7 | | | |
| Bladder Stone | 0.4 | 0.5 | | | |
| Incontinence | 2.1 | 1.7 | | | |
| Renal Failure | 0.5 | 0.6 | | | |
| UTI | 5.7 | 4.9 | | | |
Discontinuation
due to worsening
of BPH, lack of
improvement, or
to receive other
medical treatment
| 21.8 | 13.3 | | | |
Compared with placebo, finasteride was associated with a significantly lower risk for the need for BPH-related surgery [13.2% for placebo vs 6.6% for finasteride; 51% reduction in risk, 95% CI: (34 to 63%)]. Compared with placebo, finasteride was associated with a significantly lower risk for surgery [10.1% for placebo vs 4.6% for finasteride; 55% reduction in risk, 95% CI: (37 to 68%)]; see Figure 2.
Figure 2 Percent of Patients Having Surgery for BPH, Including TURP
Image Of Figure 2 (Finasteride Fig 3)
Effect on Maximum Urinary Flow Rate
In the patients in a long-term efficacy and safety study who remained on therapy for the duration of the study and had evaluable urinary flow data, finasteride increased maximum urinary flow rate by 1.9 mL/sec compared with 0.2 mL/sec in the placebo group.
There was a clear difference between treatment groups in maximum urinary flow rate in favor of finasteride by month 4 (1.0 vs 0.3 mL/sec) which was maintained throughout the study. In the earlier 1-year studies, increase in maximum urinary flow rate was comparable to a long-term efficacy and safety study and was maintained through the first year and throughout an additional 5 years of open extension studies.
Effect on Prostate Volume
In a long-term efficacy and safety study, prostate volume was assessed yearly by magnetic resonance imaging (MRI) in a subset of patients. In patients treated with finasteride who remained on therapy, prostate volume was reduced compared with both baseline and placebo throughout the 4-year study. Finasteride decreased prostate volume by 17.9% (from 55.9 mL at baseline to 45.8 mL at 4 years) compared with an increase of 14.1% (from 51.3 mL to 58.5 mL) in the placebo group (p<0.001). (See Figure 3.)
Results seen in earlier studies were comparable to those seen in a long-term efficacy and safety study. Mean prostate volume at baseline ranged between 40 to 50 mL. The reduction in prostate volume was seen during the first year and maintained throughout an additional five years of open extension studies.
Figure 3 Prostate Volume in a Long-Term Efficacy and Safety Study
Image Of Figure 3 (Finasteride Fig 4)
Prostate Volume as a Predictor of Therapeutic Response
A meta-analysis combining 1-year data from seven double-blind, placebo-controlled studies of similar design, including 4491 patients with symptomatic BPH, demonstrated that, in patients treated with finasteride, the magnitude of symptom response and degree of improvement in maximum urinary flow rate were greater in patients with an enlarged prostate at baseline.