Effectiveness of Finasteride (Proscar)
Inhibiting the enzyme that converts testosterone to dihydrotestosterone (DHT) can decrease the levels of DHT by about 70% to 80%. The reduction in DHT causes the prostate to shrink in size, which can help improve urinary flow and reduce symptoms of urgency or difficulty in urination. Peak urinary flow rate increases by about 15% to 20% in most. Nearly one-half of men taking finasteride have been shown to eventually obtain a 50% reduction in their symptom score.
Improvement is achieved after about six months to one year of treatment with finasteride. After this time, little further improvement can be expected, but the smaller size and the lower DHT levels can be maintained as long as finasteride treatment is continued. (The longest reported follow-up studies include six years of treatment.)
