What is the use of Finasteride (Propecia)?

From the Guidelines

Finasteride is recommended as a treatment option for benign prostatic hyperplasia (BPH) in patients with an enlarged prostate, as it has been shown to reduce prostate size and improve urinary symptoms, with a mean change in IPSS of -4.74 points 1.

Key Points

• Finasteride works by inhibiting the enzyme 5-alpha-reductase, which converts testosterone to dihydrotestosterone (DHT), a hormone that contributes to prostate enlargement.
• The medication is typically prescribed as a 5mg daily oral tablet for prostate issues, and treatment requires continuous use for at least 3-6 months before results become noticeable.
• Common side effects include decreased libido, erectile dysfunction, and decreased ejaculate volume, which may persist even after discontinuation in some cases.
• Regular follow-up with a healthcare provider is important to monitor for side effects and effectiveness.
• The most recent and highest quality study, published in 2021, supports the use of finasteride as a treatment option for BPH, with a moderate recommendation and evidence level of Grade C 1. ### Considerations
• Patients should be informed of alterations in PSA due to the medication, and the measured serum PSA value should be doubled after 1 year of 5-ARI therapy to accurately gauge disease progression.
• Treatment with 5-ARIs and combination therapy hinges on prostate volume and PSA threshold, and obtaining imaging with TRUS to objectively assess prostate size is reasonable.
• The larger the gland, the more pronounced the effects of finasteride, and a minimum prostate volume of >30cc or PSA >1.5ng/mL is necessary for a reliable 5-ARI response.

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.

Finasteride Mechanism of Action: Finasteride works by inhibiting the enzyme Type II 5α-reductase, which converts testosterone to dihydrotestosterone (DHT).

• It forms a stable enzyme complex with Type II 5α-reductase, leading to a decrease in DHT levels.
• The reduction in DHT levels leads to a decrease in the development and enlargement of the prostate gland.
• The maximum effect of finasteride on serum DHT concentration is observed 8 hours after the first dose 2.

From the Research

Finasteride Overview

• Finasteride is primarily used to treat benign prostatic hyperplasia (BPH) and male androgenetic alopecia (MAA) 3.
• It is a 5-alpha reductase inhibitor (5α-RI) that can induce male sexual dysfunction due to its effects on testosterone and dihydrotestosterone 3.

Side Effects of Finasteride

• There is evidence suggesting that 5α-RIs may independently increase the risk of erectile dysfunction (ED) 3.
• Finasteride has been correlated with ED in patients with BPH, but not in patients with MAA 3.
• Some studies have reported side effects of finasteride associated with sexual dysfunction, including ED, male infertility, ejaculation problems, and loss of libido, even in MAA patients 3, 4.
• Long-term use of finasteride may be associated with health risks including non-alcoholic fatty liver disease (NAFLD), insulin resistance (IR), type 2 diabetes (T2DM), dry eye disease, and potential kidney disease 5.

Efficacy of Finasteride

• Finasteride 1 mg/day has been shown to significantly increase total hair count compared to placebo after 24 and 48 weeks 4.
• The efficacy of finasteride has been demonstrated in clinical trials, with pairwise and network meta-analyses performed to assess its efficacy 4.
• A novel composition using naturally derived 5AR inhibitors has been shown to outperform finasteride in in vitro assays of representative cell lines for AGA and BPH 6.

Patient Education and Awareness

• Patients need to be educated about the possible short- and long-term side effects of finasteride 4.
• Physicians should discuss with their patients the possible long-term effects of finasteride on sexual function 3.
• Factors that may explain finasteride's inconsistency regarding its therapeutic and side effects should be further investigated and used to categorize subjects into distinct subgroups 7.