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Clinical Pharmacology
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Clinical Pharmacology

PROSCAR 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.

PROSCAR was further evaluated in the PROSCAR Long-Term Efficacy and Safety Study (PLESS), 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 PLESS had moderate to severe symptoms at baseline (mean of approximately 15 points on a 0-34 point scale). Patients randomized to PROSCAR 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 PROSCAR vs placebo (–2.3 vs –1.6), and this improvement continued through Year 4.

Figure 1
Symptom Score in PLESS


Symptom Score in PLESS - illustration

Results seen in earlier studies were comparable to those seen in PLESS. 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 Acute Urinary Retention and the Need for Surgery

In PLESS, 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 and acute urinary retention requiring catheterization. Complete event information was available for 92% of the patients. The following table (Table 1) summarizes the results.

Table 1
All Treatment Failures in PLESS


  Patients (%) *      
Event Placebo
N=1503
Finasteride
N=1513
Relative
Risk**
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
  Acute Urinary Retention Requiring Catheterization 6.6 2.8 0.43 (0.28 to 0.66) < 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
*patients with multiple events may be counted more than once for each type of event
**Hazard ratio based on log rank test
Brand Name: Proscar
Generic Name: Finasteride
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