Medical Treatment of Benign Prostatic Hyperplasia: 5α-Reductase Inhibitors and α-Adrenergic Antagonists

Abstract

Benign prostatic hyperplasia (BPH), a nonmalignant neoplasm of the prostatic epithelial and stromal tissue, occurs commonly in elderly men. The "gold standard" of care for symptomatic BPH has been and remains transurethral resection of the prostate. This operation, however, like any surgical procedure, has associated morbidity and imposes an appreciable expense on the health-care system; therefore, enthusiasm for the development of medical therapies for the management of symptomatic BPH has been substantial. Currently, practicing physicians have two types of medications for the treatment of symptomatic BPH: 5 alpha-reductase inhibitors and alpha-adrenergic antagonists. The former drugs inhibit the conversion of testosterone to the potent prostatic androgen dihydrotestosterone. As a result, the androgenic stimulation to the prostate gland is suppressed, and the size of the prostate is decreased by approximately 25%. In some patients, this outcome decreases the mechanical obstruction of the prostatic urethra and improves micturition. alpha-Adrenergic antagonists decrease the smooth muscle tone of the bladder neck, prostatic adenoma, and prostatic capsule. After these structures have been relaxed, resistance to urine flow through the prostatic urethra can be decreased, and obstructive voiding symptoms can be resolved. Although two distinctly different mechanisms are involved, both types of medications are effective for treating BPH. Thus, in 1993, transurethral resection of the prostate is no longer the only available therapeutic option. With the advent of medical therapies, internists and primary-care physicians will have more involvement in the care of patients with BPH than previously. Therefore, urologists and nonurologists must work together to serve the needs of patients with prostatism.