Family Nurse Practitioner Exam

Which medication is classified as a 5-alpha reductase inhibitor?

1. Terazosin (Hytrin)

2. Tamsulosin (Flomax)

3. Finasteride (Proscar)

4. Sildenafil (Viagra)

The correct answer is: Finasteride (Proscar)

Finasteride is classified as a 5-alpha reductase inhibitor, which is a category of medication that works by blocking the enzyme responsible for converting testosterone into dihydrotestosterone (DHT). DHT plays a significant role in the development of benign prostatic hyperplasia (BPH) and male pattern baldness. By reducing levels of DHT, finasteride effectively shrinks the prostate gland in men experiencing urinary symptoms associated with BPH and can also promote hair regrowth in those with androgenetic alopecia. In contrast, terazosin and tamsulosin are alpha-1 adrenergic antagonists, which work by relaxing the muscles in the prostate and bladder neck to alleviate urinary obstruction but do not affect DHT levels. Sildenafil, on the other hand, is a phosphodiesterase type 5 (PDE5) inhibitor, primarily used to treat erectile dysfunction by increasing blood flow to the penis. Therefore, finasteride stands out as the medication that specifically inhibits the action of 5-alpha reductase.