5α-reductase inhibitors

An overview of 5α-reductase inhibitors, their mechanism, uses, and related topics.

5α-reductase inhibitors are a class of medications that prevent the conversion of testosterone into dihydrotestosterone (DHT) by inhibiting the enzyme 5α-reductase. These inhibitors are primarily used in the treatment of conditions related to excess DHT, such as benign prostatic hyperplasia (BPH) and androgenic alopecia.

Mechanism of Action

5α-reductase is an enzyme that catalyzes the conversion of testosterone into dihydrotestosterone (DHT), a more potent androgen. DHT plays a significant role in the development and maintenance of male characteristics and is involved in the pathophysiology of several androgen-dependent conditions. By inhibiting this enzyme, 5α-reductase inhibitors reduce the levels of DHT, thereby alleviating symptoms associated with its excess.

Types of 5α-Reductase Inhibitors

There are two main types of 5α-reductase inhibitors:

• Finasteride: This drug selectively inhibits the type II isoform of 5α-reductase. It is commonly used in the treatment of BPH and male pattern baldness.
• Dutasteride: This drug inhibits both type I and type II isoforms of 5α-reductase, making it more potent than finasteride. It is used primarily for BPH.

Clinical Uses

5α-reductase inhibitors are used in the management of several conditions:

• Benign Prostatic Hyperplasia (BPH): These inhibitors help reduce prostate size and alleviate urinary symptoms by lowering DHT levels.
• Androgenic Alopecia: By reducing scalp DHT levels, these drugs can slow hair loss and promote hair regrowth in men with male pattern baldness.
• Prostate Cancer Prevention: Some studies suggest that 5α-reductase inhibitors may reduce the risk of developing prostate cancer, although this is still a subject of ongoing research.

Side Effects

Common side effects of 5α-reductase inhibitors include:

• Decreased libido
• Erectile dysfunction
• Ejaculatory dysfunction
• Gynecomastia

These side effects are generally due to the reduced levels of DHT, which is important for normal sexual function.

Also see

• Androgen receptor
• Hormone replacement therapy
• Prostate cancer
• Hair loss treatments