Finasteride

Finasteride is a synthetic 4-azasteroid compound and specific inhibitor of steroid Type II 5α-reductase, which is an intracellular enzyme that converts the androgen testosterone into 5α-dihydrotestosterone (DHT). It works in a similar fashion as dutasteride, which is another 5-alpha-reductase inhibitor, by exerting antiandrogenic effects. Finasteride is an orally active drug that was first approved by the FDA in 1992 for the treatment of benign prostatic hyperplasia to improve symptoms and reduce the risk for acute urinary retention or the need for surgical procedures. In 1998, it was approved by the FDA to treat male pattern hair loss. Finasteride is commonly marketed under the brand names Propecia and Proscar to be used aloneo or in combination with doxazosin, an alpha-blocker.

Both benign prostatic hyperplasia and androgenic alopecia are androgen-dependent disorders that are characterized by in situ high levels of DHT. In the treatment of benign prostate hyperplasia, alpha-blockers such as tamsulosin and terazosin are also used. Compared to alpha-blockers that focus on providing the rapid relief of symptoms, 5α-reductase inhibitors aim to target the underlying disease by blocking the effects of the primary androgen involved in benign prostate hyperplasia and androgenic alopecia, thus reducing the risk for secondary complications while providing symptom control.

Finasteride is indicated for the treatment of symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate to improve symptoms, reduce the risk of acute urinary retention, and reduce the risk of the need for surgery including transurethral resection of the prostate (TURP) and prostatectomy. A combination product with tadalafil is also used for the symptomatic treatment of BPH for up to 26 weeks.

Finasteride is also indicated for the treatment of male pattern hair loss (androgenetic alopecia, hereditary alopecia, or common male baldness) in male patients.