In 1992, Merck introduced a revolutionary drug finasteride (Proscar). This drug was the first drug introduced that reduces the size of the prostate, rather than treating the symptoms (like doxazosin and tamsulosin do). By reducing the volume of the prostate, the tension on the urethra caused by the enlargement of the gland is diminished and symptoms as a result of prostatic enlargement are diminished. Symptoms do not dissipate immediately when using this drug, but rather it takes 6-12 months until patients notice significant improvement in their symptoms.
This drug is in the category of a 5 alpha-reductase inhibitor (5-ARI). These drugs work by interfering with the metabolism of testosterone to a byproduct know as dihhydrotestosterone (DHT). DHT is the potent byproduct that is responsible for facial and body hair growth, deepening of the voice, and prostatic growth. DHT also plays a role in male pattern balding and acne development. The drug Propecia (a form of finasteride) is utilized for male pattern balding. By inhibiting the formation of DHT, a decrease in prostate volume is accomplished.
Long tem studies with these drugs have demonstrated a significantly decreased risk of developing urinary retention or undergoing prostatic surgery. Erectile dysfunction however has been reported in patients using finasteride. A decrease in sex drive an ejaculatory dysfunction may also be experienced. Dietary supplements such as saw palmetto also inhibit the formation of DHT, however not as specifically as the pharmaceutical products. Special attention needs to be paid to the patient's PSA while on these drugs, as there is some evidence that these drugs can interfere with the interpretation of the patient's PSA.
More recently another 5-ARI drug dutasteride (Avodart) has also been released. This drug works in a similar fashion to finasteride. The manufacturer is also working on a similar product for hair loss. This drug is reported to block a greater percentage of the DHT when compared to finasteride and patients may see improvement quicker than those using finasteride.