From the Guidelines
Finasteride is used for the prevention of prostate cancer, as well as for the treatment of benign prostatic hyperplasia (BPH) and male pattern baldness.
Key Points
- The use of finasteride for prostate cancer chemoprevention has been shown to decrease the incidence of invasive cancers in healthy people, with a relative reduction in risk of approximately 26% 1.
- The Prostate Cancer Prevention Trial (PCPT) reported a decrease in cumulative incidence of prostate cancer from 24.4% in the placebo arm to 18.4% in the finasteride arm during the 7 years of the trial 1.
- Finasteride has been shown to reduce the incidence of prostate cancer, but there is concern about the potential for an increase in high-grade cancers, although this is thought to be due to enhanced detection rather than tumor transformation or induction 1.
- The dose of finasteride currently being used to treat male pattern baldness is 1 mg per day, whereas the dose used in the PCPT was 5 mg per day, and it is unknown if the lower dose is as effective in reducing the risk of prostate cancer 1.
- PSA levels are expected to be reduced by approximately 50% in men taking finasteride, but the Panel cannot recommend a specific cut point to trigger a biopsy for men taking a 5-ARI 1.
- Finasteride is also used for the treatment of BPH and male pattern baldness, with a dose of 5 mg per day and 1 mg per day, respectively.
- The balance of benefits and harms of finasteride for the prevention of prostate cancer is complex and depends on various factors, including the individual's risk of prostate cancer, the potential for adverse effects, and the effectiveness of the treatment 1.
From the FDA Drug Label
The development and enlargement of the prostate gland is dependent on the potent androgen, 5α -dihydrotestosterone (DHT). Finasteride is a competitive and specific inhibitor of Type II 5α-reductase with which it slowly forms a stable enzyme complex. In patients with BPH, finasteride tablets have no effect on circulating levels of cortisol, prolactin, thyroid-stimulating hormone, or thyroxine.
The use of Finasteride is to inhibit the production of 5α-dihydrotestosterone (DHT), which is involved in the development and enlargement of the prostate gland. This is achieved by inhibiting the Type II 5α-reductase enzyme. The primary use of Finasteride is in the treatment of Benign Prostatic Hyperplasia (BPH) 2.
From the Research
Uses of Finasteride
- Finasteride is used to treat benign prostatic hyperplasia (BPH) by reducing the size of the prostate gland and improving urinary flow rate 3, 4, 5, 6
- It is also used to treat androgenetic alopecia (male pattern hair loss) by inhibiting the conversion of testosterone to dihydrotestosterone (DHT) 7
- Finasteride has been shown to produce significant effects in men with an enlarged prostate gland, and may arrest the progression of BPH 3
- Experimental uses of finasteride include prostate cancer prevention and treatment of other DHT-mediated disorders such as acne, facial hirsutism, and frontal lobe alopecia 3, 5
Mechanism of Action
- Finasteride works by inhibiting the 5 alpha-reductase enzyme, which converts testosterone to DHT 3, 7, 4, 5, 6
- This inhibition reduces DHT levels in target organs such as the prostate and scalp hair, without affecting circulating levels of testosterone 3
- The reduction in DHT levels leads to a decrease in prostate volume and an improvement in urinary flow rate 4, 6
Clinical Effects
- Finasteride has been shown to reduce prostate volume by 20-28% and improve urinary flow rate by 3-4 ml/s 4, 6
- It has also been shown to improve symptoms of BPH, such as decreased libido and sexual potency 4, 5
- The clinical effects of finasteride are rapid and predictable, with significant improvements seen within 12-24 weeks of treatment 6