From the Guidelines
Finasteride is recommended for the treatment of benign prostatic hyperplasia (BPH) in patients with an enlarged prostate, as it has been shown to reduce the risk of subsequent acute urinary retention and the need for BPH-related surgery, with the absolute benefit increasing with rising prostate volume or serum PSA 1. The medication works by inhibiting the enzyme 5-alpha-reductase, which converts testosterone to dihydrotestosterone (DHT), a hormone that contributes to prostate enlargement. Key benefits of finasteride include:
- Reduction in prostate size
- Improvement in urinary symptoms
- Decreased risk of acute urinary retention and BPH-related surgery However, it's essential to note that finasteride is ineffective in patients who do not have enlarged prostates 1. Potential side effects of finasteride include:
- Decreased libido
- Erectile dysfunction
- Ejaculation disorders These side effects are reversible and uncommon after the first year of therapy 1. In terms of dosage, finasteride is typically prescribed at 5mg daily for prostate issues, while a lower dose of 1mg daily is used for hair loss treatment 1. Regular follow-up with a healthcare provider is crucial to monitor the effectiveness of finasteride and any adverse effects 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 man, a single 5-mg oral dose of finasteride tablets produces a rapid reduction in serum DHT concentration, with the maximum effect observed 8 hours after the first dose.
The mechanism of action of finasteride is the inhibition of Type II 5α-reductase, which leads to a decrease in DHT levels.
- Finasteride forms a stable enzyme complex with Type II 5α-reductase, resulting in a slow turnover rate.
- The maximum effect of finasteride on serum DHT concentration is observed 8 hours after the first dose.
- Daily dosing of finasteride at 5 mg/day reduces serum DHT concentration by approximately 70% 2.
From the Research
Finasteride Overview
- Finasteride is primarily used to treat benign prostatic hyperplasia (BPH) and male androgenetic alopecia (MAA) 3.
- It works by inhibiting the conversion of testosterone to dihydrotestosterone (DHT), reducing the size of the prostate gland and the level of prostate-specific antigen (PSA) 4.
Side Effects of Finasteride
- Finasteride has been associated with sexual dysfunction, including erectile dysfunction (ED), male infertility, ejaculation problems, and loss of libido 3, 5, 6.
- The incidence of these side effects varies, with some studies reporting a higher incidence in patients with BPH than in those with MAA 3.
- Other side effects of finasteride include decreased ejaculatory volume, gynaecomastia, and depression 4, 5.
Post-Finasteride Syndrome
- Post-finasteride syndrome (PFS) is a condition characterized by persistent or irreversible sexual, neurological, physical, and mental side effects after discontinuing finasteride treatment 5.
- The exact mechanisms underlying PFS are not fully understood, but it is thought to be related to the inhibition of 5alpha-reductase and the subsequent reduction in neuroactive steroid levels 5, 7.
Guidelines for Finasteride Use
- Finasteride is considered safe for the treatment of androgenetic alopecia, but patients should be informed of the potential sexual side effects before starting treatment 6.
- Further studies are needed to fully understand the safety and efficacy of finasteride, particularly with regards to its long-term effects on sexual function 3, 6.